Delete Statistical Category Only Deletes Entries When Attached To Patrons

# Environment
* PostgreSQL 9.1.5
* Evergreen 2.2RC test server and trunk compiled at commit e8dcb2de62179fc924b340ba3230ce5bd4092c42 (oct 11)
* OpenSRF 2.10 (from trunk commit 56e5f5d796bcbf80bd8e801d523fc9e2aee3947d)
* Debian 6.0.6

# Steps to Reproduce

1. Create a Patron Statistical Category (tried both allow free text and not)
2. Add an entry value for the category
3. Fill in/Save a value for the category for a patron
4. Return to stat cat editor, edit category and hit Delete Statistical Category
5. Says Update Successful. Category still exists on refresh but Entries are deleted from actor.stat_cat_entry.

# Expected

1. Denied deletion error due to patrons still having value assigned, including entries. Should be an error / alert for this case. This seems the route since actor.stat_cat_entry_usr_map references actor.stat_cat

Previous bug report #818271 states that there is no link between the entry side which still seems correct with the tables I'm seeing. I can understand the entries being deleted since the value is really free text. However if the category deletion is going to be blocked it doesn't seem like the entries should be deleted either and at a minimum an error stating why the category wasn't deleted should be shown.