Update cloudsearchdomain to the latest version

Fixes aws/aws-cli#943
Fix failing tests

When switching to sigv4, the region _is_ required.
These tests are updated appropriately, one to not use a sigv4
service, the other, to verify we raise an NoRegionError because
we didn't provide an error.
Merge branch 'update-cloudsearchdomain' into develop

* update-cloudsearchdomain:
  Fix failing tests
  Update cloudsearchdomain to the latest version