Users can now be gotten by slug
Test coverage for GETting users by slug
Anonymous users can have the same name
Corrected sending errors in auth
User name slugs can now be unset by emptying their name
Anonymous users are now silently renamed upon signup in case of conflict
Added a test case for unsetting slugs (and fixed related bug)
Name conflicts migration script.
Merge branch 'master' of https://github.com/codecombat/codecombat
Merge branch 'nameable_users' of https://github.com/rubenvereecken/codecombat into rubenvereecken-nameable_users
Merge branch 'rubenvereecken-nameable_users'