embedding repo in binary

Now is possible to embed git repo directly in binary, and then read from
this repo _without_ extracting it into temporary folder! Such speed!

It makes possible to rollback grapes version if needed from any node as
long as it can be done without recompiling go sources (e.g. when changes
takes place only in configs or in templates).

Also, it provides beautiful way to test dev version of grapes without
commiting/repacking binary.