WIP: Berksfile support

Reworked Berksfile support. There is one more thing to solve to properly use Berkshelfe we should not use any local cookbooks and only use cookbooks from Berksfile. Otherwise I use temporary directory for berks vendor if it's not said other way.

1) README
2) tests 

Will be done after initial approval.
Do we want to output stuff even on success or only on failure?