Improve unit testbed

[jonaf]

Right now we have an extremely simplified template that we use for our test. We should add some kind of test for the larger example template (https://github.com/bazaarvoice/cloudformation-ruby-dsl/blob/master/examples/cloudformation-ruby-script.rb) so that new contributions can be added to the example template and the test can be updated. This way new contributions don't have to do a ton of work to add test coverage for their changes.