Mitigation for CVE-2017-0889.

https://www.cvedetails.com/cve/CVE-2017-0889/
https://medium.com/in-the-weeds/all-about-paperclips-cve-2017-0889-server-side-request-forgery-ssrf-vulnerability-8cb2b1c96fe8

- premailer gem to turn CSS into inline styles automatically
- rework UserMailer templates
- reword UserMailer templates

* Add confirmation step for email changes

This adds a confirmation step for email changes of existing users.
Like the initial account confirmation, a confirmation link is sent
to the new address.

Additionally, a notification is sent to the existing address when
the change is initiated. This message includes instruction to reset
the password immediately or to contact the instance admin if the
change was not initiated by the account owner.

Fixes #3871

* Add review fixes

* Remove rabl dependency

* Replicate old Oj configuration

* Update active_model_serializers to version 0.10.7

* Update capistrano-rails to version 1.3.1

* Update capistrano-rbenv to version 2.1.3

* Update capybara to version 2.16.1

* Update devise-two-factor to version 3.0.2

* Update i18n-tasks to version 0.8.19

* Update ox to version 2.8.2

* Update parallel_tests to version 2.19.0

* Update puma to version 3.11.0

* Update redis-namespace to version 1.6.0

* Update rspec-rails to version 3.7.2

* Update scss_lint to version 0.56.0

* Update webmock to version 3.1.1

* Update webpush to version 0.3.3

* bundle update

jwt 2.1.0 still does not work well.
ref. https://github.com/zaru/webpush/issues/42

* Update better_errors to version 2.4.0

* Update binding_of_caller to version 0.7.3

* Update bootsnap to version 1.1.5

* Update browser to version 2.5.2

* Update capistrano to version 3.10.0

* Update capistrano-bundler to version 1.3.0

* Update capistrano-rbenv to version 2.1.2

* Update capybara to version 2.15.4

* Update cld3 to version 3.2.1

* Update fabrication to version 2.18.0

* Update fog-openstack to version 0.1.22

* Update kaminari to version 1.1.1

* Update lograge to version 0.7.1

* Update nokogiri to version 1.8.1

* Update oj to version 3.3.9

* Update ox to version 2.8.1

* Update parallel_tests to version 2.17.0

* Update pkg-config to version 1.2.8

* Update rspec-rails to version 3.7.1

* Update rubocop to version 0.51.0

* Update scss_lint to version 0.55.0

* Update sidekiq to version 5.0.5

* Update sidekiq-scheduler to version 2.1.10

* Update tzinfo-data to version 1.2017.3

* Update webpacker to version 3.0.2

* bundle update

* Close connection when succeeded posting

* Update webmock

* Bump ruby version to 2.4.2

https://www.ruby-lang.org/en/news/2017/09/14/ruby-2-4-2-released/

Gemfile.lock is also updated.

TODO
- [ ] Update Dockerfile with Alpine release of ruby-2.4.2

* Revert jwt version

It seems that jwt 2.0.0 fails in some environment.
ref. https://github.com/zaru/webpush/issues/42

* Bump Ruby version on docker image

Bumps [puma](https://github.com/puma/puma) from 3.9.1 to 3.10.0.
- [Release notes](https://github.com/puma/puma/releases/tag/v3.10.0)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](https://github.com/puma/puma/compare/v3.9.1...v3.10.0)

Bumps [rails](https://github.com/rails/rails) from 5.1.3 to 5.1.4.
- [Commits](https://github.com/rails/rails/compare/v5.1.3...v5.1.4)

* Fix language filter codes

CLD3 returns BCP-47 language identifier, filter settings expect
identifiers in the ISO 639-1 format. Convert between formats,
and exclude duplicate languages from filter choices (zh-CN->zh)

* Fix zh name

* Add handling of Linked Data Signatures in payloads

* Add a way to sign JSON, fix canonicalization of signature options

* Fix signatureValue encoding, send out signed JSON when distributing

* Add missing security context

* Update twitter-text to version 1.14.7

* Update tilt to version 2.0.8

* Update statsd-instrument to version 2.1.4

* Update sidekiq to version 5.0.4

* Update sidekiq-scheduler to version 2.1.8

* Update sidekiq-unique-jobs to version 5.0.9

* Update redis-activesupport to version 5.0.3

* Update rails-settings-cached to version v0.6.6

* Update pkg-config to version 1.2.4

* Update parallel_tests to version 2.14.2

* Update jsonapi-renderer to version 0.1.3

* Update i18n-tasks to version 0.9.16

* Update httplog to version 0.99.7

* Update fabrication to version 2.16.2

* Update bootsnap to version 1.1.2

* Update aws-sigv4 to version 1.0.1

* Update aws-sdk-core to version 2.10.21

* Update hashdiff to version 0.3.5

* Update rails to version 5.1.3

- No masking of HTTP::Error and OpenSSL::SSL::SSLError
- No longer accepts non-HTTPS WebFinger endpoints

* Refactor ResolveRemoteAccountService

* Remove trailing whitespace

* Use redis locks around critical ResolveRemoteAccountService code

* Add test for race condition of lock

* Add dependency on idn-ruby to speed up URI normalization

* Use normalized_host instead of normalize.host when applicable

When we are only interested in the normalized host, calling normalized_host
avoids normalizing the other components of the URI as well as creating a
new object

- Use unicode when selecting emoji through picker
- Convert shortcodes to unicode when storing text input server-side
- Do not convert shortcodes in JS anymore

* feat: Register push subscription

* feat: Notify when mentioned

* feat: Boost, favourite, reply, follow, follow request

* feat: Notification interaction

* feat: Handle change of public key

* feat: Unsubscribe if things go wrong

* feat: Do not send normal notifications if push is enabled

* feat: Focus client if open

* refactor: Move push logic to WebPushSubscription

* feat: Better title and body

* feat: Localize messages

* chore: Fix lint errors

* feat: Settings

* refactor: Lazy load

* fix: Check if push settings exist

* feat: Device-based preferences

* refactor: Simplify logic

* refactor: Pull request feedback

* refactor: Pull request feedback

* refactor: Create /api/web/push_subscriptions endpoint

* feat: Spec PushSubscriptionController

* refactor: WebPushSubscription => Web::PushSubscription

* feat: Spec Web::PushSubscription

* feat: Display first media attachment

* feat: Support direction

* fix: Stuff broken while rebasing

* refactor: Integration with session activations

* refactor: Cleanup

* refactor: Simplify implementation

* feat: Set VAPID keys via environment

* chore: Comments

* fix: Crash when no alerts

* fix: Set VAPID keys in testing environment

* fix: Follow link

* feat: Notification actions

* fix: Delete previous subscription

* chore: Temporary logs

* refactor: Move migration to a later date

* fix: Fetch the correct session activation and misc bugs

* refactor: Move migration to a later date

* fix: Remove follow request (no notifications)

* feat: Send administrator contact to push service

* feat: Set time-to-live

* fix: Do not show sensitive images

* fix: Reducer crash in error handling

* feat: Add badge

* chore: Fix lint error

* fix: Checkbox label overlap

* fix: Check for payload support

* fix: Rename action "type" (crash in latest Chrome)

* feat: Action to expand notification

* fix: Lint errors

* fix: Unescape notification body

* fix: Do not allow boosting if the status is hidden

* feat: Add VAPID keys to the production sample environment

* fix: Strip HTML tags from status

* refactor: Better error messages

* refactor: Handle browser not implementing the VAPID protocol (Samsung Internet)

* fix: Error when target_status is nil

* fix: Handle lack of image

* fix: Delete reference to invalid subscriptions

* feat: Better error handling

* fix: Unescape HTML characters after tags are striped

* refactor: Simpify code

* fix: Modify to work with #4091

* Sort strings alphabetically

* i18n: Updated Polish translation

it annoys me that it's not fully localized :P

* refactor: Use current_session in PushSubscriptionController

* fix: Rebase mistake

* fix: Set cacheName to mastodon

* refactor: Pull request feedback

* refactor: Remove logging statements

* chore(yarn): Fix conflicts with master

* chore(yarn): Copy latest from master

* chore(yarn): Readd offline-plugin

* refactor: Use save! and update!

* refactor: Send notifications async

* fix: Allow retry when push fails

* fix: Save track for failed pushes

* fix: Minify sw.js

* fix: Remove account_id from fabricator

* Specs for language detection

* Use CharlockHolmes instead of NKF

* Correct mistakes

* Correct style

* Set hint_enc instead of falling back and strip_tags

* Improve specs

* Add dependencies