improved code formatting for some samples (using PEP8 guidelines)

Sorry, I haven't found any code guidelines for the cocos2d project.
I propose to reformat at least some non-critical code (like samples or documentation) to [PEP8](http://python.org/dev/peps/pep-0008/)-compatible format. 
Is that acceptable?

The reformatted examples are in the 5accfd9 commit in my pep8 branch.