Don't rely on too many options for is :rateable. Instead, use DataMapper property presence to decide on which was previously decided via different options to is :rateable. This ideally makes usage of dm-is-rateable more consistent with what seems to be a DataMapper convention: List all model properties within the class body instead of automagically creating them. This makes perfect sense to me, be it a convention or not.
…_helper.rb. Also updated README.textile and added README.txt