Updates a pipeline with the provided attributes.
		Args:
			key			required identifier for the pipeline
			pipeline	StreakPipeline object
			return		(status code, pipeline_dict)

def update_pipeline(self, pipeline):
		'''Updates a pipeline with the provided attributes.
		Args:
			key			required identifier for the pipeline
			pipeline	StreakPipeline object
			return		(status code, pipeline_dict)
		'''
		#req sanity check
		payload = None
		if  type(pipeline) is not StreakPipeline:
			return requests.codes.bad_request, None

		payload = pipeline.to_dict(rw = True)

		try:
			uri = '/'.join([
						self.api_uri,
						self.pipelines_suffix,
						pipeline.attributes['pipelineKey']
						])
		except KeyError:
			return requests.codes.bad_request, None
	
		code, r_data = self._req('post', uri , json.dumps(payload))

		return code, r_data