PSC-STM-B5: Monitoring of PSC Transformer

[tiredpixel]

Since it should be running continuously, it is important to get notifications of when it has crashed.

It ought to be recovering if it is a brief crash, since the stream pointer is stored so it can resume from where it was. However, frequent crashes could show something need fixing, and a long outage could lead to the stream data no longer being available (a sign we will need to ingest the bulk S3 data to get any missing data).

Add monitoring so that some notification is sent for whenever it goes down and uptime status.

Estimate: 1 hour

[tiredpixel]

Noting here that I'm going with the conclusions of #247 . That means using Airbrake, at present, but with the flexibility to change quite easily if the need arises (e.g. it becomes too expensive).