Fixing Bug 1858 and Bug 1673 with changes in net-virt package

1. Adding support for pool-id based on fix that went into the controller/
northbound/networkconfig/neutron for fixing Bug 1673

2. Fixing issue where LB pool member creation / deletion fails when VIP
isn't created yet

3. Incorrect handling of the events (missing "break" in switch statement)

4. Adding missing Activator .setInterface for LBaaS handlers

Change-Id: Ied854fe4f44c839a1e46036e625b7fb3cf3111cc
Signed-off-by: Srini Seetharaman <srini.seetharaman@gmail.com>