[Breaking] Support Vagrant 1.1+ and remove vagrant gem dependency.

A new strategy is used here when dealing with Vagrant: each Kitchen
Instance gets its own dedicated Vagrantfile which is rendered out just
before any Vagrant CLI commands are invoked. In this way we can avoid
writing a vagrant plugin and we return any Vagrantfile in the project
root back to the user to fully control.

An isolated Vagrant sandbox is created for each Instance in a an
internal directory under .kitchen/. For example, given an Instance name
of "default-ubuntu-1204", a Vagrantfile will be created in:

  .kitchen/kitchen-vagrant/default-ubuntu-1204/Vagrantfile
Apply simplifying assumption of only supporting Vagrant 1.1 and up.
Update Vagrant#login_command to return a LoginCommand object.

This is the upstream API update needed to change directory before
issuing the SSH command to connect to a Test Kitchen controlled Vagrant
VM. Coolbeans.
Merge pull request #7 from opscode/no-vagrant-gem

[Breaking] Support Vagrant 1.1+ and remove vagrant gem dependency.
Add #verify_dependencies implementation.

Currently this check will look for the following:

* Is Vagrant installed at all?
* Is Vagrant's version 1.1.0 or later?
* If a Berksfile exists, is the berkshelf-vagrant plugin installed?
Merge pull request #8 from opscode/verify-dependencies

Add #verify_dependencies implementation.
Update README badges.
Add CHANGELOG.
Release 0.7.0, free the Vagrant gem!
Release 0.7.1, gemspec edition.
Up version for development.
Update Code Climate badge on README.
Wrap strings for data_bags_path and roles_path in Vagrantfiles.
Release 0.7.2.
Up version for development.
[Bugfix] Calling #destroy should not memoize #create_vagrantfile.

This edgecase happens when a instance already exists and `kitchen test`
is called on that instance. Since the test action always calls destroy,
and destroy cleans up the vagrant root directory, we want to re-create
the directory and Vagrantfile when the create action is invoked.

Super thanks to @sandfish8 for helping to reproduce!!!
Release 0.7.3.
Up version for development.
Drop `vagrant ssh -c` & communicate directly via SSH.

This was done by calling `vagrant ssh-config` after the instance is
created which returns the SSH configuration required to make further
connections. This configuration is saved off into the state bag just
like any other SSH-based driver.

Thanks to an upstream API change
(https://github.com/opscode/test-kitchen/commit/a37c2c61f341a88e840438c31136eac49453ca0b)
SSH configuration can come from .kitchen.yml or from the saved instance
state.
Release 0.7.4.