mbs-6201: add constraint for collection types
More info on merge edits, show default icon for events
Merge remote-tracking branch 'reo/collection-type-constraint' into schema-change-2014-q4

* reo/collection-type-constraint:
  mbs-6201: add constraint for collection types
Merge remote-tracking branch 'reo/events-nitpicks-2' into schema-change-2014-q4

* reo/events-nitpicks-2:
  More info on merge edits, show default icon for events