AFS Quota checking functionality for drupal user messages.

* Adds a check to hook_init for once a day checking of the file storage limit
* Adds a report to the system reports page
* Adds a manual check bypass page at admin/config/stanford-sites-helper/afsquota/check
* Adds a check to hook_file_insert
* Adds a check to hook_file_update
* There is no hook to be called on file_unmanaged_save_data or file_unmanaged_copy so anything outside the files table will have to be picked up by the daily check.