make-snapshot action, to make hard copies of project with all deps.

I write prototype of locking dependency via copy all stuff from deps/
(using git-archive and hashed taken by same way as regular lock-deps do).

This code heavy inspired by riak Makefile.
Code still need some care from me (add testing, and may be add checking/enforcement all repos to be committed/pushed), but I think I reach point where I need review from someone.