Tests for babel transforms

Include tests to check babel transforms.

Ideally, we should be able to test it for various babel versions (for instance, 5.x and 6.x). Challenge: have npm to install multiple babel version. jQuery UI [uses bower](https://github.com/jquery/jquery-ui/blob/master/Gruntfile.js#L256). [TodoMVC repo](https://github.com/tastejs/todomvc/) addresses that with a subdirectory with its own package.json file. See comments at https://github.com/jquery-support/globalize-compiler/pull/12#discussion-diff-51297036