VRRPv3 Interoperation with VRRPv2

RFC 5798 states that VRRPv2 and VRRPv3 interoperation is optional, and that mixing these two versions should only be done when transitioning from VRRPv2 to VRRPv3.

VRRPv2 and VRRPv3 interoperation should not be implemented as a permanent solution.

This release supports configuration for the following modes of operation: VRRPv2, VRRPv3, and VRRPv2 and VRRPv3 interoperation.