working update schedule policy

When schedule policy is updated, its respective entry in scaling_schedule is also updated

Need to add more tests
added more tests
Initial verification for server deletion
Verification happens in a loop until the server has been deleted
Actually call verified delete from delete_server
fix lint
uncommented AUTO-467 tests

and removed disallow_update tests.
Also fixed status code check after successful update
Move verify Deferred into the scope that actually uses it
Move some general utility things to test utils
Make a mock logger that will make sure no extra methods can get called, and that should make testing logging a little easlier
Clarify mock_log docstring as to how and why to use it
Remove airbrake usage.
Remove airbrake dependency, opt_requirements, and all references to opt_requirements.
Fix lint.
Fix docstring of mock_log
test refactoring - per @cyli

having a method to validate only policy update calls and seperate method to validate update made in
scaling_schedule table
Removing checking of select calls when get_policy is called since that has been seperately tested.
Instead mocking it
Removed AUTO-467 reference
Merge pull request #308 from rackerlabs/auto-488-check-if-nova-deletes-servers

Auto 488 check if nova deletes servers
Merge pull request #311 from rackerlabs/auto-486-remove-airbrake

Auto 486 remove airbrake
Merge pull request #302 from rackerlabs/schedule_policy_update

AUTO-467: update schedule policy