Merge branch 'feature/thread-muting' into 'develop'

lib/pleroma/notification.ex

lib/pleroma/thread_mute.ex

lib/pleroma/web/common_api/common_api.ex

lib/pleroma/web/mastodon_api/mastodon_api_controller.ex

lib/pleroma/web/mastodon_api/views/status_view.ex

lib/pleroma/web/router.ex

priv/repo/migrations/20190205114625_create_thread_mutes.exs

test/web/common_api/common_api_test.exs

test/web/mastodon_api/mastodon_api_controller_test.exs