Add support for Ubuntu Trusty in Vagrantfile
Add support for Ubuntu Trusty in Vagrantfile

Allow an Ubuntu distribution to be specified in the Vagrantfile.

When Trusty is specified, use the official Puppetlabs Vagrant box for
Ubuntu Trusty, pulled down from Vagrant Cloud:

https://vagrantcloud.com/puppetlabs/boxes/ubuntu-14.04-64-puppet

alphagov/ci-puppet,alphagov/ci-puppet,alphagov/ci-puppet,boffbowsh/ci-puppet,boffbowsh/ci-puppet,alphagov/ci-puppet,boffbowsh/ci-puppet,boffbowsh/ci-puppet