use PubSub JWT auth for security instead of the hardcoded static key

Author: JoshuaFox

TODO.md

@@ -4,11 +4,7 @@
 
 * P2 Memory consumption: Even an empty AppEngine app (not Iris, just a Hello World with 3 lines of code in total) crashes on out-of-memory for the smalled AppEngine instance. Google has confirmed this. See if there is a workaround.  This will save money.
 
-* P2 PubSub push endpoint security:
-  Note: The token by itself is not very secure, though   Google has at times recommended this approach.
 
-  [Use JWT](https://cloud.google.com/pubsub/docs/push)
-
 
 * P3 Label immediately after an event in certain cases, as opposed to using a daily cron as is now done.
     * Cloud SQL Instances