JCLOUDS-126  swift-keystone support for regions 

To address https://issues.apache.org/jira/browse/JCLOUDS-126

I'm still rather new to JClouds and guice, I've done my best to align with the JClouds code style but would appreciate any feedback :)

The only glaring omission is a missing unit test for SwiftKeystoneApiMetadata.java, it seemed to be only tested indirectly via other integration tests so I wasn't sure of the best way to go about designing a test for the class. If you could offer any suggestions I'd be happy to incorporate them into this request.