added word_unc_injector post module

Module for injecting UNC paths into word .docx documents.

This post module modifies an external .docx file on either Linux or Windows,
by downloading it locally, injecting an UNC path, and re-uploading. Requires
meterpreter shell. 

The injected UNC path can point to a capture or relay 
server where netNTLM credentials will be submitted once the document
is opened. These then can be used for relay or password attacks. 

More info about the module and its usage: http://jedicorp.com/?p=534