Adding editing of users for admins.

This includes both the proper API call as well as the front-end to support
editing users. This also includes the addition of the admin checkbox.
Fixing style and user tests.
Adding a test for admin option.
Handing logout and adding a web client test for user.
Merge remote-tracking branch 'origin/master' into admin_user_checkbox

* origin/master:
  Removing debugging output.
  Set parallel level back to 4.
  Fixing CherryPy version to 3.3.0
  Some travis and ansible fixes.
  Adding the installation of libffi-dev. Fixes #239.
Merge pull request #248 from girder/admin_user_checkbox

Admin user checkbox
Merge remote-tracking branch 'origin/master' into oauth-plugin
Ensure highlighting of nav links stays consistent