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.
this is valid, but using `+` is more idiomatic, like:

```
vprint_status("Received challenge from server: " +
                     "[#{data.unpack('H*')[0][0..30]}...]")
```
the leading spacing on the 2nd line is a matter of debate though.  I like to align or nearly align, but often people will just indent it once from the start of the previous line.  I guess what I do depends on the length of the 2nd line too, I'll do the regular indenting if that'll keep the 2nd line from becoming a 3rd line.