Test the field-first api for gets/sets/deletes
Merge pull request #96 from cpennington/test-field-first

Test the field-first api for gets/sets/deletes
Add is_set_on to Fields, which calls through to field_data.has (in parallel to read_from and write_to)
Rename arguments to field methods for clarity
Rename model arguments
Add utility field datas
Merge pull request #92 from cpennington/field-is-set-on

Add is_set_on to Fields, which calls through to field_data.has (in parallel to read_from and write_to)
Merge pull request #99 from cpennington/utility-field-datas

Add utility field datas