Unasync OpenStack Nova and Extension APIs

This PR un-asyncs the OpenStack Nova API, related extension APIs and updates dependent code.

Nova is now deasynced *before* Keystone, which was the approach taken in PR #380 

https://issues.apache.org/jira/browse/JCLOUDS-40

We could deprecate this method for the one with the *correct* signature. This is one of those APIs with mixed return types. Gah!