Remove last traces of AwfulSyncService, remove old interfaces, convert PM task to request.

AwfulSyncService is now completely gone, all the old callbacks have been removed, and onPreferenceChange is now in it's own interface so we don't have a pile of empty loadingWhatever methods.

Closes #201

Minor PM changes:
-Converted send-PM task to request.
-Fix title for inbox/sent folder.
-Font size tweak.