Stunner - Events UI Simplification

Given that:
1) Not all events has Input/Output configuration
2) In cases where the event has Input/Output configuration, "only one single input" or "only one single output" is configurable. (and not both of them)

It was decided to simplify the Events configuration forms in order to show Input/Output parameters configuration when it makes sense. (i.e. depending on the even nature)

The following screenshot is an example for the "Escalation Events" and was discussed/agreed with UX.

(full discussion thread can be found here: https://issues.jboss.org/browse/JBPM-7418)