authn: Use new is_headers_auth function.

authn: Deprecate the is_container_auth function.

authn: Rename 'container' -> 'headers' in authentication.

authn: Log a warning message if fallback authentication plugin is enabled in ini file.

authn: Fix container auth in login view.

authn: Fix ordering of authentication plugins.

authn: Fix form validation of authentication plugins. - Check if plugin exists. - Display an apropriate error message if it doesn't exist.

admin: tweak usergroup settings ui for clarity

permissions: show overridden permissions in permission summary page

auth-token: added missing renderers for token plugin