Adds IVS unit tests for new VIF firewall logic

Adds new unit tests for the IVS VIF driver to
cover the various possible plugging behaviors
added by the vif_details based logic introduced
in change I3bbcfc67036ab7389c82720add0bc0fc627bfee0.

Closes-Bug: #1301087
Change-Id: I7f0a1460b948a852c2d61d24217bbf27a4d85859
Don't store duplicate policies for server_group

It doesn't make sense to store same policies in a server_group.
We need to deny this usage in server_group creation.

Change-Id: I4f3ad544aef78cbbc076c7a47cca04832a2f5b4b
Closes-Bug: #1324348
Merge "Don't store duplicate policies for server_group"
Merge "Adds IVS unit tests for new VIF firewall logic"