Added Debian and Ubuntu boxes and Ansible provision.

Vagrantfile:
- Added 'boxes' dict with Debian, Ubuntu and CentOS boxes configs;
- Using private addresses on VMs so we no longer need
  port-forwarding, which would complicate maintaining multiple VMs
  for testing;
- Using Ansible for provisioning.

psdash.yml:
- Simple Ansible playbook that installs psdash and its dependencies
  in Red Hat and Debian bases OS.

.gitignore:
- Added vagrant artifacts.
Merge pull request #2 from mtpereira/more_boxes

Added Debian and Ubuntu boxes and Ansible provision.