restapi : close api gaps for operation using id and name (#890329)

Update host can use cluster id and not cluster name

This patch lets the user specify cluster id or name for updating a vm.

Change-Id: I0827f5984d630db540f2415e32c1e8e685996b38
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=890329
Signed-off-by: Ravi Nori <rnori@redhat.com>