Embed provider config in generated box files

* Add vagrant templates to the generated boxes
* Pull provider specific code out of mainline vagrant file
* Remove the multi-machine nonsense
Cleanup locales, doc, and apt caches
Hide `stdin is not a tty` message
Set id of private_network in vagrant-local.tpl

This allows us to override the private_network in the outer Vagrantfile

Signed-off-by: Kris Hicks <krishicks@gmail.com>
Document Vagrantfile overrides

Signed-off-by: Adam Stegman <astegman@pivotal.io>