Sync users to cases

Add functionality to sync a mobile worker user to a case record. This will create/update a case whenever a user is edited. For ticket http://manage.dimagi.com/default.asp?61778


This feature is part of the larger call center functionality http://manage.dimagi.com/default.asp?61733

Some new fields on project settings page:

![screen shot 2013-06-03 at 5 09 53 pm](https://f.cloud.github.com/assets/152134/602114/f73ccd0c-cc91-11e2-8638-c88849023d18.png)