Merge branch 'master' into glitch-soc/master

Conflicts:
- `README.md`:
  We have different README files. Discarded upstream changes.
- `app/views/layouts/admin.html.haml`:
  Conflict due to glitch-soc theming system.
  Adapted upstream changes.
- `app/views/layouts/embedded.html.haml`:
  Conflict due to glitch-soc theming system.
  Adapted upstream changes.
- `yarn.lock`:
  No real conflict, glitch-specific dependency too close to
  an updated one. Adapted upstream change.

config/locales/doorkeeper.en.yml

@@ -38,6 +38,7 @@ en:
         application: Application
         callback_url: Callback URL
         delete: Delete
+        empty: You have no applications.
         name: Name
         new: New application
         scopes: Scopes

config/locales/simple_form.en.yml

@@ -163,14 +163,14 @@ en:
         text: Why do you want to join?
       notification_emails:
         digest: Send digest e-mails
-        favourite: Send e-mail when someone favourites your status
-        follow: Send e-mail when someone follows you
-        follow_request: Send e-mail when someone requests to follow you
-        mention: Send e-mail when someone mentions you
-        pending_account: Send e-mail when a new account needs review
-        reblog: Send e-mail when someone boosts your status
-        report: Send e-mail when a new report is submitted
-        trending_tag: Send e-mail when an unreviewed hashtag is trending
+        favourite: Someone favourited your status
+        follow: Someone followed you
+        follow_request: Someone requested to follow you
+        mention: Someone mentioned you
+        pending_account: New account needs review
+        reblog: Someone boosted your status
+        report: New report is submitted
+        trending_tag: An unreviewed hashtag is trending
       tag:
         listable: Allow this hashtag to appear in searches and on the profile directory
         name: Hashtag