Fix EventProducerFactory without event-producer.yaml

Since the event message reduction it was no longer
possible to retrieve an EventProducer when not
having an event-producer.yaml file. This commit
restores that behaviour. It also turns off the default
event reduction for anything other than the
HornetQEventProducer
Update EV and PV screenshots for Yamcs user manual
Merge pull request #30 from fqqb/small-stuff

Small stuff