Controller fails when we can't reach emap #19

Waveform controller fails when it can't access emap database, like this

psycopg2.OperationalError: connection to server at "uclvldddtaeps02" (xxx.xxx.xxx.xxx), port xxxx failed: FATAL: the database system is in recovery mode
...
pika.exceptions.ChannelClosedByBroker: (406, 'PRECONDITION_FAILED - delivery acknowledgement on channel 1 timed out. Timeout value used : 1800000 ms.

• Decide what to do in this case. We could just keep restarting the controller until it works, or it would probably be better to just pause until we can access emap again.