restapi: display indication if vm is in run-once

Added a field to the VM REST query to indicate if the
vm is running in run-once mode.

Change-Id: I69a502a196aed2382acc35302004ea3b7cd89909
Bug-Url: https://bugzilla.redhat.com/1158357
Signed-off-by: Eldan Shachar <eshachar@redhat.com>