Fix EmsOpenstack.verify_credentials sleeper bug

There's a bug in the way that the auth_type is merged into the options used by
EmsOpenstack.verify_credentials.  Fortunately, it's obscured by the conditional
assignment operator on the first line of the method.

Now the options are merged into the original hash.

This fix will be hard to test since there is no demonstrable way to produce an
actual problem.
Merge pull request #142 from blomquisg/openstack_verify_credentials_bug

Fix EmsOpenstack.verify_credentials sleeper bug