Add 2-leg configuration to Radware LBaaS Driver

Add 2-leg configuration to Radware LBaaS Driver

Radware's load balancer currently supports three network interfaces.
Prior to this code addition, the configuration of those three
interfaces was: one interface for management, one for high
availability backup, and one for load balancing servers where the
IP that the outside world sees (VIP) and the IP that the servers
respond to (PIP) are identical.

This change adds a new "2-legged" configuration: one interface for
management, one interface for a VIP network, and one interface for the
PIP and the high availability backup network.

During VIP creation, the LBaaS driver detects if the incoming
configuration is "2-legged" by comparing VIP and PIP networks.  If they
are different it allocates a new port on the PIP network in order to
obtain an IP address for the PIP and names that port after its
associated VIP ID.  vDirect is then directed to create a load balancer
with the PIP network also used as the HA network instead of using the
vDirect container's default HA network configuration.

During VIP deletion, the LBaas driver detects if a port for the PIP
had been previously allocated by searching for and deleting port names
that map to the VIP ID.

Change-Id: Ifb93159c654f16958842f646c119479c465230f9
Closes-Bug: 1268728