EventMachine based UDP proxy.

Example usage:

> em-udp-proxy -a 127.0.0.1 -p 5001 -A 192.168.1.1 -P 5001

Starts the proxy binded to 127.0.0.1 with port 5001 and forwards traffic to/from 192.168.1.1 on port 5001.

TODO:
1. More documentation :-)
2. Remove Client objects for inactive clients (after certain threshold).
3. Add some way to get stats from it.