Upgrade grunt

First off, thanks for making this and open-sourcing it! We are planning to use it soon at AxisPhilly.

There were some big changes to Grunt with how plugins work and with some of the configuration syntax when it reached v0.4.0. This pull request updates the grunt tasks and plug-ins to work with the grunt v0.4.1.

Now, if you are running the tasks independently, the `min` task is run as `$ grunt uglify`, and the `lint` task is run as `$ grunt jshint`. The `concat` and `qunit` tasks run with the same commands as before.

A couple things to note:
- The linting task is failing because of a bunch of formatting errors in `newsquiz.js` and the qunit task is failing because the `newsquiz.html` is out-of-date and the tests are bad, but this pull request is just focused on upgrading grunt, and not fixing those two things.

- The contribution section of the `README` mentions that files in `dist` are generated by grunt and should not be modified. However, the original grunt tasks, and the grunt tasks included in this pull request, output `newsquiz.js` and `newsquiz.min.js` to the `demo\js` directory and not the `dist` directory.