http://codecombat.com/cla
It just grants us a non-exclusive license to use your contribution and certifies you have the right to contribute the code you submit. For both our sakes, we need this before we can accept a pull request. Don't worry, it's super easy.
For more info, see http://codecombat.com/legal.