fixed impacted integration tests

Some changes to API behaviour we weren't handling correctly in our integration tests:

 - [x] the default commit status result now returns a non-null value
 - [x] deployments now try to auto-merge `master` by default - which breaks the tests
 - [x] [creating a deployment](https://developer.github.com/v3/repos/deployments/#create-a-deployment) no longer supports the `Force` parameter - marked as obsolete