Second attempt at fixing #96

This one fetches the actual relation definition from the model's class
to find out if it's supposed to be used as a list.
manually merging #105
fixing column name per #99
Merge pull request #106 from pyfarm/guidow-to_dict_fix_attempt2

Guidow to dict fix attempt2 (closes #105, closes #96)
Merge branch 'master' of github.com:pyfarm/pyfarm-master into simple_validator
first implementation of validate_json
adding tests for new validate_json