Support multiple active fwrd policies on a domain

[emanoelxavier]

OSC supports grouping VMs on a security group and bind that security group to a security appliance. When this is done OSC, calls the SDN plugin to create an inspection hook. For Nuage this inspection hook is mapped to a fwrd policy. This means that for each binding OSC needs to create an active fwrd policy.
Nuage does not support multiple active fwrd policies unless they have different priority. The plugin currently leverages the priority approach as a workaround for this.
We believe that Nuage should support this concept either by support multiple fwrd policies under one domain or support the concept of grouping policy entries within a fwrd policy.