New tincd post-auth BOF exploit module

A pull request to get some feedback. I'd appreciate if you comment as well on the following:
- additional class in module (if it should be relocated, an example would be helpful, e.g. which mixins etc.)
- puts calls in the additional class
- exploit development and other comments welcome?
- Fedora ROP is on my TODO list (but I wanted to contribute the module before Christmas/holidays)
- Although I left "average ranking" in there, the exploit works for all targets with several tested (meterpreter, reverse_tcp, exec) payloads on the first execution run and is therefore very reliable.
ruby doesn't use camel case, suggest refactoring :metakeyState for :metakey_state