Some tests

This partially kicks off #17. There's not a lot of tests here (it just tests `.filter()`), but it's a start. Apart from having more assertions:

 - I added grunt-cli to devDependencies to make travis work.
 - I added a .travis.yml, though I haven't added this repo to travis yet.
 - (bonus: added an .editorconfig to dictate the code writing styles.)