title: Airflow python client
body: <p>We have some applications running and we want to start using airflow. From the documentation it seems that the only way to start a DAG is over command line. Is this true?</p>
  
  <p>For example we have a flask server running and we want to start some workflow controlled by airflow. How can we achieve this? Is there an API to trigger e.g.: <em>"Run DAG now with parameters x,y,h"</em>?</p>