1. Add new property function in the ApplicationMixin to indicate if Postgres is connected
2. Add a new guard in the RequestHandlerMixin to check that Postgres is connected prior to executing a query, raising a 503 if it is not
3. Catch OperationalError in RequestHandlerMixin and return 503 for it
4. Timeout when waiting on the connection when attempting to reconnect
5. Log when we're creating a new pool
6. Add debug logging to trace when connectios open
7. Add tests that ensure reconnect logic works as expected