add support for require_chef_omnibus driver option

[schisamo]

This option works just like it does in kitchen-ec2. It ensures the
desired version of Chef is installed via the official Opscode Omnibus
client package.

The main reason for adding this is to allow projects to use the official
Canonical published Vagrant base boxes:

http://uec-images.ubuntu.com/vagrant/

These base boxes do not ship with Chef pre-installed.

This change has been verified as working with the following .kitchen.yml:

driver_plugin: vagrant
platforms:
- name: ubuntu-12.10
  driver_config:
    box: canonical-ubuntu-12.10
    box_url: http://uec-images.ubuntu.com/vagrant/quantal/current/quantal-server-cloudimg-amd64-vagrant-disk1.box
    require_chef_omnibus: 11.4.0
  run_list:
  - recipe[apt]
- name: ubuntu-12.04
  driver_config:
    box: canonical-ubuntu-12.04
    box_url: http://uec-images.ubuntu.com/vagrant/precise/current/precise-server-cloudimg-amd64-vagrant-disk1.box
    require_chef_omnibus: 11.4.0
  run_list:
  - recipe[apt]
suites:
- name: default
  run_list:
  - recipe[hubot]
  attributes: {}

[fnichol]

Ah, totally right! I've got a commit inbound for test-kitchen to address test-kitchen/test-kitchen#32 as well

[lxndrp]

It seems that this feature is gone again; I couldn't find any reference to it on the master tree. This is somewhat a pity, because it badly interacts with the current box default which points to provisionerless VMs.