Add initial AbstractDataQuery model and related parser.

Also included in this commit are limited tests on the new code.
Add tests for full coverage of the data query parser
Add a new manager for the DataQuery class
Fix json extraction bug in __init__
Add DataQuery class and associated tests
Fix validate and parse bugs and add tests for DataQuery coverage

This fixes the problem where None was always being returned from calls to validate ClassMethods. Also, the DataQuery object had to self.json reference because it stores the json in two separate fields. The code has been updated to build a temporary json object from those fields.
Style fix -- keep arguments on same line as much as possible
Merge pull request #108 from cbmi/query

Implement (Abstract)DataQuery and parser