Add User to Group from User Screen

copies the scheduled report UI to add a way to add users to groups directly from the user page

in response to http://dimagi.uservoice.com/forums/194748-user-management/suggestions/3474131-add-user-to-group-from-user-screen
and http://dimagi.uservoice.com/forums/194748-user-management/suggestions/4292318-option-to-assign-mobile-worker-to-group-when-creat

![image](https://f.cloud.github.com/assets/66555/1143788/2d105d96-1d59-11e3-9af5-03b77b48ca27.png)