Remove Access-Control-Allow-Origin in pleroma.nginx

See merge request !424

Unify Mastodon Login with OAuth login.

See merge request !429

Runtime configured router

See merge request !426

Get rid of Pleroma.Config in favor of Application

See merge request !428

Same API as the old Pleroma.Config

This removes duplication in the login code.

Discussed in !426 (comment 7232)

Use the same example domain and use it as variable

See merge request !423

Runtime emojis: Fix wrong return when finmoji is disabled

See merge request !427

Runtime configured emojis

See merge request !425

The changes are a bit heavy since the emojis were loaded into module
attributes from filesystem.

This introduces a GenServer using an ETS table to cache in memory the
emojis, and allows a runtime-reload with `Pleroma.Emoji.reload()`.

Test for null-content activities.

See merge request !422

Add CORSPlug to make web-based OAuth easier.

See merge request !420

Pleroma.Web.MastodonAPI.StatusView: Content isn’t nullable

See merge request !421

Test for case-insensitive mastodon hashtag timelines.

See merge request !419

Fix hashtag search

See merge request pleroma/pleroma!418

When we lowercase the search it will succesfully do a case insenstive
match. Now #Linux will match #linux and #LINUX whereas previously it
would only match the exact case.

Check for empty string in_reply_to ids.

Closes #355

See merge request pleroma/pleroma!417