Ignore sending VM subscribes for ServiceInstance VMs, Interface port-type
attribute distinguishes Nova created VMs and ServiceInstance VMs.

Bug # 1398116

Change-Id: I422380cd6a72138618b43e37ef378145d976b53e
Merge "Ignore sending VM subscribes for ServiceInstance VMs, Interface port-type attribute distinguishes Nova created VMs and ServiceInstance VMs." into R2.0