vagrant; issue #441: Improve main config including aws ubuntu lts dependency

This pull request refactors our main Vagrantfile to use Ubuntu 12.04 TLS and docker PPA with major cleanup. It has been verified to work with vagrant 1.0.4+ for vagrant precise64 box  (http://files.vagrantup.com/precise64.box) and vagrant 1.2.1 for ami-d0f89fb9 (ubuntu/images/ebs/ubuntu-precise-12.04-amd64-server-20130411.1).