Added the mutator class, which mutates attribute values.
Added the parse module, which contains a function to parse an ATTRIBUTE-MUTATOR-DICT.
Removed the Mutator.to_json() method, which made no sense at all.  Added Mutator.__ne__() method, since I already have __eq__.
Added parse.attr_dictr, the reverse of parse.attr_dict.
Added the Schema class.
Updated Schema to keep track of its default mutator, and output it in JSON.
Added the Person class.
Added hash to Person.