Added support for fossil SCM, added recipe for vc-fossil.el, a VC backen...

I added support for melpa to use the fossil SCM (you may need to install the software on your servers first). I also added a new recipe for vc-fossil, which is the vc integration emacs with fossil. This software is not written by me, but by Venkat Iyer <venkat@comit.com>.  The main repo is at http://chiselapp.com/user/venks/repository/emacs-fossil/ 
I am just a user of vc-fossil, my only contribution was an enhanced request, which is still not implemented.

I know, these are 2 changes in 1 request, but you need both to test them out.