Switch to Ansible for provisioning hosts file

The vagrant-hosts plugin was assigning the hostnames to 127.0.1.1, which
was causing issues with MySQL bind addressing. Instead, use a hosts file
uploaded by Ansible that does what we want.
Remove external network from network-node

Keeping the public network interface in the network-node caused network
configuration to take around 5 minutes on each boot. Since this is a
lab, and the VMs can get out anyway, removing the directive for now.
Reogranize ansible groups, add os_controller playbook
Add common configuration and admin-openrc

All the machines should have access to the admin-openrc file, just in
case. Also separate the common configuration into it's own file, and the
controller has it's own playbook.