Djangomodelimport

- Added JSONField support. Similar to FlatRelatedFields, but combines multiple columns into a single dict to pass to a JSONField on the current model instead. Columns are passed in as `myfield_a`, `myfield_b`, `myfield_c`, which is converted to `myfield = {'a': data, 'b': data, 'c': data}` then saved in the `myfield` JSONField on the model.
- Refactored some magic form code to not pollute the form definition.
- Added tests! 🎉

New arguments to ModelImporter.process:
- allow_updates=True
Allow existing instances to be updated
- allow_inserts=True
Allow the creation of new instances
- limit_to_queryset=None
A queryset of objects that are allowed to be updated

- Fixed another bug with DateTimeParserField where it would prematurely raise an error for an empty field.

- Fixed a bug with stripping `None` in `DateTimeParserField`.

- Changed package name on PyPI to have hyphens: `django-model-import`

Initial release.