Added grunt linting

Automated linting of our files is a good idea for a distributed development environment. This commit added the necessary packages for the grunt task-runner and configured it for linting our javascript.
Added travis-ci integration

Automated tests ftw, with this commit also indicating that the non-programming travis configuration has been completed.
Fixes #17: JSON list of audio URLs in playlist.json
Expand track details in playlist.json per review
Add playlist.json to grunt linting