Straw man commit to discuss GetComputeEndpoint.

A few questions about this commit:

1. Is NovaApiMetadata the best place for GetComputeEndpoint?

2. What's the best first parameter to pass into NovaApiMetadata.getServerURI(Utils ...)?
Preferably I would pass in something I can call getUtils() on but Context and ComputeServiceContext are incompatible.

3. How best to test this?