Session timeout after idle session

This commit is the UI portion of the session timeout feature for 2.4 (not incorporating the session_limit yet). This includes actively ending a session when the user's session time has expired, as well as giving the user a notification one minute prior that their session is about to end. It also includes removing 'session_timeout' from config.js. This is now retrieved from the response headers of each REST call. Each time the user make a rest call the session is extended another 1800 seconds (or whatever amount the user might configure with AUTH_TOKEN_EXPIRATION in local_settings.py)

awx/ui/client/tests/directives/job-status-graph-test.js

@@ -4,7 +4,7 @@ import '../support/node';
 
 import {describeModule} from '../support/describe-module';
 import 'shared/Utilities';
-import 'shared/RestServices';
+
 import JobStatusGraph from 'dashboard/graphs/job-status/main';
 
 var resizeHandler = sinon.spy();