Add module for the dlink user-agent backdoor

Module written mainly by @m-1-k-3, just helped him a little. He asked me to do pull request because was not able to do it atm.

So here it is :) for the recent backdoor found in the dlink devices: http://www.devttys0.com/2013/10/reverse-engineering-a-d-link-backdoor

Tested on DIR-100 device with firmware version v1.13 devices. Ask me privately for pcap for verification!