Creates a box field with the provided attributes.
		Args:
			box_key			specifying the box to add the field to
			name			required name string
			field_type		required type string [TEXT_INPUT, DATE or PERSON]
			kwargs			{}
			return			(status code, field dict)

def create_box_field(self, box_key, name, field_type, **kwargs):
		'''Creates a box field with the provided attributes.
		Args:
			box_key			specifying the box to add the field to
			name			required name string
			field_type		required type string [TEXT_INPUT, DATE or PERSON]
			kwargs			{}
			return			(status code, field dict)
		'''
		#does not work
		self._raise_unimplemented_error()
		
		uri = '/'.join([self.api_uri,
						self.boxes_suffix, 
						box_key,
						self.fields_suffix
						])
		
		code, data = self._create_field(uri, name, field_type, **kwargs)
		
		return code, data