Merge pull request #2709 from techAPJ/patch-2

FIX: allow localization in timestamp
FIX: Use the `bumped_at` date for the RSS feed for a topic
FIX: RSS feeds should use `created_at` not `bumped_at`
FIX: Retain back button scroll position even if we don't load more.
UX: Add link to change username on admin page
FIX: Double clicking quote expansion shouldn't break stuff.
FIX: Better boundary checking for emoji
PERF: Do far fewer checks and use a lot less memory when loading more
FIX: uncategorized counts were always 0. topics_year, topics_month, topics_week, topics_day
FIX: topicCountStats was depending on the wrong properties
Add a message to the staff logs indicating why a user was purged
FIX: Don't show topics as unread when hitting back
HACK: remove jarring scroll when hitting back from topic
Update Translations