Add ZoneMinder arbitrary command execution exploit

Add ZoneMinder arbitrary command execution exploit module.

* Source: http://www.zoneminder.com/
* Tested on 1.25.0 (Ubuntu Linux)

![ZoneMinder Video Server arbitrary command execution vulnerability](http://www.itsecuritysolutions.org/2013-01-22-ZoneMinder-Video-Server-arbitrary-command-execution-vulnerability/exploit.png)