Extracted nickname registration into a private controller method
Added strings

Added some strings not yet existing in the "es" locale but already in use in the application.
Extract ListController#list_target_user
improved specs for avatar
Show Private Messages pill as a topic list rather than individual messages.
add a warning whenever the uploaded image is not a square
Russian translation (actual version)
Merge pull request #1375 from versvs/master

Added strings
Merge pull request #1379 from abbat/master

Russian translation (actual version)
Merge pull request #1376 from gcapizzi/lists_controller_refactoring

ListController refactoring
Merge pull request #1371 from einarj/cleanup_user_registration

Extracted nickname registration into a private controller method
Merge pull request #1377 from ZogStriP/avatar-work

Improved specs for avatar + added a warning whenever the uploaded image is not a square