GUACAMOLE-723: Move getClientIdentifier() to GroupListItem for convenience of other uses of the guacGroupList directive.

guacamole/src/main/webapp/app/groupList/groupListModule.js

@@ -21,4 +21,8 @@
  * Module for displaying the contents of a connection group, allowing the user
  * to select individual connections or groups.
  */
-angular.module('groupList', ['list', 'rest']);
+angular.module('groupList', [
+    'navigation',
+    'list',
+    'rest'
+]);