Add goods

This adds the concept of an item to the game. You can buy and use items, and the current only items exist in the fast food restaurant. To test:

1. Start Game
2. Move to Fast Food Restaurant
3. Get a Job
4. Work
5. Buy an item
6. Use item

You should see your fatness go up, since hunger is already at 0.

This fixes #57, make sure you include that in the merge comment.