Make sure that v2 api tests have the policy file configured

Change-Id: I2533f4f1724aa4ae9808ff0d533f49c0ef42afe4
vnics: don't presume existence of filterref/filter

With quantum/ovs plugin, there is no necessarily a "filteref" in interface param.
If not present don't lookup the "filter", let it to None and no more use
vnics.fref as resource_id.
resource_id becomes : instance_name + instance_uuid + vnic_name

fix Bug #1180466

Change-Id: I21c15f9ee4bd5303a7f2e287c7fe69aa7d0d5b0a
Merge "vnics: don't presume existence of filterref/filter"