Support to do list of hypervisors in detail

1. Added another model to capture Hypervisor in detail
2. Added another action to list hypervisor in detail in client.
3. Added hypervisor_hostname attribute to server.
4. Converting hypervisor_version from int to string while
   building the model.Changed corresponding unit tests

Change-Id: Ib62f8bc807e01e5a3d2b5dcc773b24c7a8c12fe8
Merge "Support to do list of hypervisors in detail"