Summary: I'd like us to start having some decent testing at the packager/bundler level to check that there are no major breakage hapenning. This changeset introduce a simple test that just test the `buildBundle` public API. On the same model, I'd like to test the server API and behavior, and things such as hot module reloading. I hope this will also highlight the gross inconsistencies of the API, for example the Bundle/BundleBase hierarchy, that we can proceed to fix later.
Reviewed By: davidaurelio, cpojer
Differential Revision: D5121817
fbshipit-source-id: e0f3758c7fbb7a85cf51fb3cbc34c12d5374b7d3