Overhaul DHCP check to handle broadcast, and do unicast as a dhcp relay
- Separate listening and sending sockets - fixes some broadcast issues
- If server set, use unicast, but set giaddr and listen on dhcp server port
- Add debug output (incoming and outgoing DHCP messages are displayed)
Merge pull request #463 from mrichar1/dhcp

Overhaul DHCP check to handle broadcast, and do unicast as a dhcp relay