found a retain cycle when calling trigger on an object. it is
due to Hash.new, a bug in rubymotion that will be fixed in the next
release: http://hipbyte.myjetbrains.com/youtrack/issue/RM-203.
adding specs to show retain cycle currently occurs when calling #trigger.
not using Hash.new for Eventable fixes the retain cycle until this
bug is fixed: http://hipbyte.myjetbrains.com/youtrack/issue/RM-203
fix failing ns notification spec