enable user to link coursemology account with their facebook account in the setting page.
Merge branch 'master' of github.com:Coursemology/coursemology.org

* 'master' of github.com:Coursemology/coursemology.org:
  fix for logo proposition problem
  fixed update user profile error page
added testing code for User model
adding debug info in development env
added user sign up page testing
added authentication page testing cases
added redirect to sign up  when not signed in
change from feasible to general in welcome page