Improvements to apt bootstrapping

- Don't use stages to get PPAs and apt-get update to run first; instead rely on
  explicit relationships between resources and resource types.
- Use /vagrant/apt-cache as APT cache for quick VM re-creation.
- Make 'running' the default ensure for Service resource.

Change-Id: I19385f5e1e630af5a74cce6284e853a39fc7d62b