ISIS-831: AbstractInteractionEvent now has a userData hash

... to allow phases to pass information between each other, without coupling the publisher as to how its subscribers might want to interact.
ISIS-835: fixed NPE, drop down for strings now ok for actions...

... though still has an issue as a property (new value is just ignored).
ISIS-837: remove guard which prevents flushing of properties that have NotPersistedFacet.class

(eg annotated with javax.jdo.annotations.NotPersistent)