Remove vagrant-berkshelf in favour of librarian-chef

Since, `vagrant-berkshelf` is now deprecated (https://sethvargo.com/the-future-of-vagrant-berkshelf) it is now necessary to move chef cookbooks management to `vagrant-librarian-chef`.

I changed the vagrant box used to a newer version. There are no noticeable benefits.
Merge pull request #1 from uehondor/remove-berkshelf-in-favour-of-librarian-chef

Remove vagrant-berkshelf in favour of librarian-chef