Openucb-259: Add cas authenticated admin step to install profile

* Adds Setup UC Berkeley Administrator step
* Create admin will only accept numeric CAS UIDs
* If you create a CAS admin, the final step will send you to CAS login for the site.
* If you skip creating a CAS admin, the final step will log you into the site as user1.
* Works with drush site install
* Optionally supports comma-separated uids in either the webform or a 'drush site-install' command.

Example drush site-install commad:
```
drush -y @local.openberkeley-drops-7 site-install openberkeley --site-mail=brianwood@berkeley.edu --site-name="OB Test" --account-mail=bwood+01@berkeley.edu --account-name=ucbadmin --account-pass=t update_status_module='array(FALSE,FALSE)' cas_add_user_form.cas_name=212372,213108
```