Improvements designed to make automated boxes easier. Includes:

* Vagrantfiles fixed to have predictable names
* test/runner.sh now knows how to publish a box to s3
* Extracting secrets for developers into ~/.laptop.secrets
* Error reporting improvements
* Full documentation on creating new base boxes

We now require vagrant >= 1.5.0 to use the automated test suite built
into laptop.
Ubuntu 14.04 LTS (Trusty Tahr) support