Moved password from user down to identity
Reviewed Authentication and Identity
Added OmniAuth for twitter
Added more OAuth-providers
Added testsecrets for travis
Fixed coverage [ci skip]
Expire cache for production
Fixed missing authentication on sign in

  When a user enters an email-address of an omniauth-user with
  a password. No authentication (:identity) will be found for the
  email. The thrown exception is now caught.
Refactored SessionController
Added SignUpInvitation model and mailer

  not finished yet!
  TODO: Refactor Settings
  TODO: Complete ActionMailer setup
  TODO: Controllers for Invitations
Fixed text of invitation mail
Refactored Settings module
Refactored SettingsError
Configured Mailserver, refactored Settings
Updated README
Added invitation for omniauth
Completed YARD
Added SignUpInvitationsController