Use the host resolver as a DNS proxy
Use the `vagrant-hostmanager` plugin.

`vagrant-hostmanager` is a Vagrant plugin that manages the `/etc/hosts` file on guests within a multi-machine environment.
Minor reorganization of `Vagrantfile`
Added a `phabricator-db` host
Use the `vagrant-cachier` plugin.

`vagrant-cachier` shares a common package cache among similiar VM instances.
Use the `vagrant-auto_network` plugin.

This plugin takes care of assigning IP addresses (within a default pool range of 10.20.1.2/24) to vagrant machines.
Use a more common name for the manifest file
Don't require the `vagrant-cachier` plugin
Use the `fqdn` core fact instead of passing around a hostname.

See http://docs.puppetlabs.com/facter/latest/core_facts.html#fqdn