Added abstract meta property to enforce abstract bases
changed get_rpeo_path to get_data_path
make sure model is registered in workspace
Serialize model name with serialized models
Renamed GitModel.get_path to GitModel.get_data_path for clarity and consistency
Changed id_field to id_attr, since we are allowing any attribute to act as the id
Added test for GitModel.all()
Fixed bug that caused duplicate fields when overriding a field named id and not using that field as the id_attr