We dont need bats on the dev vm anymore
Bump dev dependencies
Update example vagrantfile to test vagrant-cachier integration
Validate if the docker image has been set right before creating the container

This fixes an issue where a `vagrant up` fires up a base box download
and we don't know beforehand if the command has been set from the base
box `Vagrantfile`.
Allow ports to be specified from the `Vagrantfile`
Do not hardcode path to base box used on acceptance specs
Vagrant 1.4 uses Ruby 2.0.0