FEATURE: allow staff to send multiple invites to same email
Merge pull request #2603 from techAPJ/patch-1

FEATURE: allow staff to send multiple invites to same email
FIX: Was not filtering correctly on the user's stream
FIX: Display proper error message when changing a trust level fails
FIX: User email was changing in the HTML  when you invited a user
FIX: Response is no longer forbidden with JSON errors for changing trust
level.
Merge remote-tracking branch 'upstream/master' into german-locale