Added module for Freesshd Authentication Bypass (CVE-2012-6066)

This module works against FreeSSHD <= 1.2.6. Tested against
password and public key authentication methods. It will generate
a random key and password.

To use it you need to know a valid username. The module contains
a basic bruteforce methods, so you can specify more than one to try.
Merge branch 'freesshd_authbypass' of https://github.com/danielemartini/metasploit-framework into danielemartini-freesshd_authbypass
final cleanup