adds opts.success callback to internal didDestroy callback
Merge pull request #525 from ryanjduffy/patch-5

Fixes ENYO-3480 - enyo.Model.destroy doesn't fire callbacks
Merge branch 'core' into model-store-fixes
use cheaper method of determining changed state for firing event

Enyo-DCO-1.1-Signed-off-by: Cole Davis <cole.davis@lge.com>