Added ability to switch OF roles per DPID or for all switches at once. This includes a REST interface and integration with the handshake and channel handlers in order to keep the switch in the correct state. An IOFConnectionListener also has the ability to listen for messages that are written now instead of read from the wire. This allows modules to write role requests, have the underlying handshake/channel substrate tap in and listen to the request, and automatically update the role of the switch when the response comes back.