title: How do I add a new connection type to Airflow?
body: <p>Looking at the plugin documentation (<a href="https://airflow.incubator.apache.org/plugins.html" rel="noreferrer">https://airflow.incubator.apache.org/plugins.html</a>), it is clear how to add to new hooks and operators, but I am adding a new hook that requires connection information.  This information seems to be hard-coded in <code>airflow/models.py</code>.  Is there a way to add my own connection type to the list without altering Airflow's source code?</p>