core : Search VMs based on MAC address

Users should be able to search for VMs from Webadmin-Portal
Search bar using a search query filtering on mac address:

Vms: Vnic.mac = 00:1a:4a:b4:9b:a8

Change-Id: I42229383647c4494ffab75af1ad6e619ad02fe5f
Bug-Url: https://bugzilla.redhat.com/1016916
Signed-off-by: Ravi Nori <rnori@redhat.com>