Allow sub interfaces to be created on a virtual interface
Allow sub interfaces to be created on a virtual interface

To support multiple logical interfaces on top of a single physical interface
inside the VM (primarily, vlan interfaces), have an equivalent representation
within vrouter too by allowing sub interfaces to be created on top of the
virtual (VM's tap) interface too.

Change-Id: Id83678b936a5d6988a218adc84e47410a6afb800

srajag/contrail-vrouter,codilime/contrail-vrouter,srajag/contrail-vrouter,codilime/contrail-vrouter,srajag/contrail-vrouter,codilime/contrail-vrouter,codilime/contrail-vrouter