Add a license file - MIT

Per discussion in GitHub issue #346, we're applying the MIT license
to the VVV project, copyright the contributors of the VVV project.
Make note of MIT license in the VVV Contributing document
Add copyright / license note to README
Merge pull request #453 from Varying-Vagrant-Vagrants/new/license

Apply the MIT License to VVV

So happy.

Fixes #346