More levels

This pull request includes seven new levels, bringing the total up to 15 :)

All of the platforms in these levels are of the sizes listed in #29. Many of these levels encourage the usage of platforms, too, so have fun with that :) I also changed the order of the levels to hopefully provide a smoother difficulty curve.

Also, have a screenshot :) This level does look familiar, but...
![a familiar level](https://f.cloud.github.com/assets/1811645/433757/1bc0cb00-aeed-11e2-81a0-46ae6073726f.png)