Port to Grunt 1.4

This PR updates the build setup of dataflow to Grunt 1.4. Some options (like QUnit tests and the dev server runner) have been omitted because the tests don't appear to be in the repository.

In addition, there is configuration for Travis CI. With Travis, each push to the repository will be built and tested (in this case just linted), which is handy when you get external contributions.

To enable Travis for your official repo, you need to log into http://travis-ci.org and enable the repo there.