SNMP4J: How to send and receive traps

How to use the SNMP4J API for send and receiving traps by Joel Patrick Llosa

Developed in Windows 7 but should work on other OSs.

To use:

1. Open a command prompt and start the `SnmpTrapListener` to start listening for SNMP traps. Prints out the trap details when received.
2. Open another command prompt and run `SnmpTrapSender` to send traps.