Add tests up to `Player.eat`

The closure was removed so that the tests could actually
see the code.

The order of the comments in `zombies.js` was changed so to make
writing the code more succinct.

Instead of calling `runGame` directly, it's called after the tests are run on
line 20 of index.html.
Merge pull request #1 from thgaskell/tests

Add tests up to Player.eat