Use ubuntu-lxc apt_repo for Ubuntu 12.04
Update Berksfile for compatibility with Berkshelf 3+
Reduce default VM memory to 4096 MB
Change kitchen provisioner to chef_zero
Comment out synced_folders
Use ruby-install and chruby instead of ruby-build and rbenv.
Specify emacs package per platform_version
Add ubuntu-12.04 platform to .kitchen.yml
Use Official Ubuntu Vagrant boxes

I couldn't get ruby-lxc gem to install on Chef's Ubuntu 14.04 bento box.
The box hasn't been updated recently so it isn't using 14.04.1. For some
reason I had to upgrade libcgmanager0 package to be able to get ruby-lxc
to install. Without the upgrade the following would fail.

ruby -r mkmf -e "p find_library('lxc', 'lxc_container_new')"
checking for lxc_container_new() in -llxc... no
false

So I figured I might as well switch to the Official Ubuntu Vagrant box
which is a daily build so it has 14.04.1. And while I was at it I might
as well use the Official Ubuntu Vagrant box for 12.04.
bump version to 0.2.0