amd + umd support

Hello!

This PR adds basic support for AMD and UMD that is already in video.js and missing in this plugin.
I've slightly updated jshint config file to pass tests.
the global variable is `videojs`. However, in this case, we're in CommonJS land (browserify) and videojs's [npm name](https://www.npmjs.org/package/video.js) is `video.js`.