added down platform, new art, and changed stars to 3 different types of cheeses

Platform and player speeds now increases in time with a speed modifier.
some Images resolutions lowered. Game size issue fixed (vertical length
is a little bigger than screen to hide address bar on iPhone 4).
Platforms are generated by randomly selecting a surrounding platform.
Currently adding a store
store now changes value of cheeses and changes a new "overall score"

working on new spike art