add vagrant-berkshelf plugin and let it manage the cookbook path on vagrant-up
use https URLs for github so it works behind a Proxy
lock all dependencies in metadata.rb, use stable vagrant-ohai v1.0.0 version
Merge pull request #8 from tknerr/lock-deps

Lock all Dependencies in metadata.rb
Merge pull request #7 from tknerr/vagrant-berkshelf

add vagrant-berkshelf plugin and let it manage the cookbook path