VMware: fix instance rescue bug

Commit I6448cb929e9afce814d0580eada91b8fd37befa3 added object support
to the rescue operations. This exposed a bug in the VMware driver
which was caught by the minesweeper. A rescue instance is named
'<instance-uuid>-rescue'. In the past this name was updated on the
instance, now it is passed as a parameter to the spawn method.

Change-Id: I633614c6c634d41a32a9b1b70d941e9bfdcadedd
Closes-bug: #1278149
Merge "VMware: fix instance rescue bug"