3rdparty/ for collection of 3rd-party git submodules

Actually this is probably more for discussion than for the merge -- although if everyone thinks it is a good idea we could proceed merging it in.

@LyleScott :  I remember some time back someone already made similar "extension" to fail2ban but I even forgot who and where.  

So may be we could keep a 3rdparty/ collection with knowing to work with current version version extensions of various kinds which are not necessarily supported by us?