Redesigned User class so that it could work as an object (adding and saving attributes, added delete method, and lets it save a session token). Required changing UserQuery as well. Added a few appropriate test cases in TestUser class. Finally, added ParseError exception class. Addresses issue in #5.
Added details of User class to README.mkd. Added exception if APPLICATION_ID or REST_API_KEY is not set. Changed parse to parse_rest in a few lines of the docs.
Added ability to access a parse_rest.Object like a dictionary or an iterable, along with test cases for that functionality.