tree c914c43439806239bfb629d1f0a9fab4c133da1e
parent 6c050693b6ac5a067013baadce62007e42678b6c
author Matthew Barth <msbarth@us.ibm.com> 1515700429 -0600
committer Matthew Barth <msbarth@us.ibm.com> 1520365515 -0600

Make event actions optional

Event actions should be made optional for events that only require
subscribing to group signals.

This is in preparation for separating signal and timer based event
actions. A use case would be where one event can be used to subscribe to
signals that update cached property values without performing an action,
and another timer based event performs an action based on those
property values the signal event provides.

Tested:
    Events without an action are generated correctly
    Events without an action are handled correctly and run no action

Change-Id: I757a82ce6c45ac637ce7cea8f82a62b98b600e3e
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>