Fixup signin and signout

No Issue
* Move authentication related handlers to the Application route.
* Switch Sign Out from a button to a link.  Use the signout route
  to handle invalidating the session and redirecting instead of
  an action from a button.
* Clear error messages on signin page when pressing log in button.
* Errors are now always shown on sign in screen and a success
  notification is shown after sign out.
* Update functional tests.