Hook up pending system for writes

Whenever a user with "write with audit" privileges attempts to
write a field:
1. The write will not throw any sort of exception
2. The field on the model will be rolled back to the original
   value
3. An audit with will be created with a "requires_auth" flag set
   to true, signifying that this audit represents a pending action

A future commit will add the ability to query and apply the pending
audits