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
uncommented AUTO-467 tests

and removed disallow_update tests.
Also fixed status code check after successful update
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 #302 from rackerlabs/schedule_policy_update

AUTO-467: update schedule policy