Implement authentication via Riyosha

 - Consolidate authentication configuration
 - Implement shunting
   - Forced login for browsers that has once logged
     in via DTU CAS
   - Hinted login for users that has successfully logged in once
 - TODO: User management is functional, but does not display correct user info
 - TODO: User switching is functional, but currently expects Riyosha
         user ids in the form instead of cwis, email, name, etc.
Update rails to 3.2.14
Only show tags and bookmarks for authenticated users
Send omniauth log messages to Rails logger