engine: Added setVmName() to VmNetworkInterface mapper

Got lost among the VNIC profile patches and caused a minor UI bug.

Change-Id: I0f83a7f6aac644d7a59998ad88b1ef2aead73b5f
Bug-Url: https://bugzilla.redhat.com/1000297
Bug-Url: https://bugzilla.redhat.com/1000306
Signed-off-by: Lior Vernia <lvernia@redhat.com>