GUAC-955: Add element module and guacScroll directive. Refactor guacFocus to element module. Use guacScroll to update menu scroll during drag.

guacamole/src/main/webapp/app/login/loginModule.js

@@ -23,4 +23,4 @@
 /**
  * The module for the login functionality.
  */
-angular.module('login', []);
+angular.module('login', ['element']);