Upates box field as specified
		Args:
			box_key		key for pipeline where the fields lives
			field 				StreakField object with fresh data
			returns				(status code, updated field dict)

def update_box_field(self, box_key, field):
		'''Upates box field as specified
		Args:
			box_key		key for pipeline where the fields lives
			field 				StreakField object with fresh data
			returns				(status code, updated field dict)
		'''
		#does not work
		self._raise_unimplemented_error()
		
		uri = '/'.join([self.api_uri,
						self.boxes_suffix,
						box_key,
						self.fields_suffix
						])
		return self._update_field(uri, field)