bump ruby version used in kitchen tests
switch from jamie to test-kitchen 1.0
add canonical's 12.04 image as a platform

This image is slightly different than the opscode box as it has system
ruby pre-installed. This ends up affecting how we install foreman
force foreman to install under chef's rubygems

The canonical 12.04 image has ruby pre-installed, at which point chef
installs foreman under system ruby instead of omnibus ruby.

Whether using chef's ruby for foreman is a good idea or not is out of
the scope of this commit, but should be addressed in the future.