Makes write_graphite plugin usable outside client_graphite recipe.
Take into account the fact that Ubuntu 12.04 has changed the arch specific directory structure.
Make plugin dir logic a little cleaner so it passes tailor tests.
Update chef and ruby versions.
Update Gemfile to reference newer test-kitchen, and also load busser and busser-minitest.
Introduce test for installed package version
Don't specify version if we're installing from package.