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

@zack-shoylev My preference would be to have all of the API methods return primitive types across the board. That's me though... ;) Deprecate/add this method as well? WDYT?