VMWare: add power off vm before detach disk during unrescue

Non Hot Plug type disk like IDE can only be detached when the VM is power off.

Change-Id: Ib1f387a41abe2b52357854e90c2535ebb7b43f18
Close-bug: #1279199
(cherry picked from commit 1e1915aaaca38b5691794e0e052a42b9d95dd3c2)
VMware: ensure rescue instance is deleted when instance is deleted

If the user creates a rescue instance and then proceeded to delete
the original instance then the rescue instance would still be up
and running on the backend.

This patch ensures that the rescue instance is cleaned up if
necessary.

The vmops unrescue method has a new parameter indicating if
the original VM should be powered on.

Closes-bug: 1269418
(cherry picked from commit efb66531bc37ee416778a70d46c657608ca767af)

Conflicts:

	nova/virt/vmwareapi/vmops.py

Change-Id: I3c1d0b1d003392b306094b80ea1ac99377441fbf
Merge "VMWare: add power off vm before detach disk during unrescue" into stable/icehouse
Merge "VMware: ensure rescue instance is deleted when instance is deleted" into stable/icehouse