Create automation job for sending notifications to users about followed locations

[maxachis]

Follows :

• 478

part of: #26

To implement the above endpoint properly, an automation job will need set up which can take subscribed users and send them notifications about updated data requests and sources.

This requires several other components:

1. A working and long-term v2 database (as of this writing, the only v2 databases are refreshed from v1 production daily)
2. Obviously, this automation job will do nothing if there are no users following anything.

Other things to consider:

• This notification job is designed to run once a month, so it would be a while between setup and when we could actually see it play out as expected in a production environment.
• Hence, it'll probably be a good idea to create test cases in a beta v2 environment, where we:
  • Have one of us follow several locations
  • Add real or test data requests and/or data sources to those locations
  • Manipulate the database entries of these events so that they are the month prior
  • Run the endpoint to confirm that emails are sent.

[josh-chamberlain]

The only thing keeping us from a proper v2 beta is #32, IMO.