Log significant info using Python logging module

We would like to log significant events using Python's logging module and eventually send specific notifications to Slack. For our purposes we want to log:

1. When the doc_type isn't understood so that:
- Dev team can add keyword if it is appropriate.
- Could be a question instead or a tip-off for newsroom to follow up with.
2. When an error occurs e.g ElasticSearch is down or the nurses website is down.