restapi : memory_policy-guaranteed option doesn't exists in 'add vm' autocompletion

From cli --memory_policy-guaranteed option doesn't exists in
'add vm' autocompletion options, when it passed it is
working (should be added to autocompletion options)

Change-Id: I1e201343a782e0fb947ce3055a304db03950d6dd
Bug-Url: https://bugzilla.redhat.com/962447
Signed-off-by: Ravi Nori <rnori@redhat.com>