use base controller query_params method

refs: CNVS-392

Since all the auditor controllers use this same method it was
moved to the audit api base class.  See CNVS-392(g/27807).
This also adds the grade_change record method to activate the
submissions shard when creating a record which should will
prevent some shard issues with it.

Test Case:
  - Test the API calls for grade changes
  - Test the API calls for authentication events

Change-Id: If89d6b14cb7d328128b3a2275134301014d87ed3
Reviewed-on: https://gerrit.instructure.com/28551
Reviewed-by: Rob Orton <rob@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Nick Cloward <ncloward@instructure.com>