Added dispatchToParents method for contexts

Events bubble to all ancestors in sequence. Data payload may be enriched along the way. If stopPropagation:true is added to data payload, bubbling stops. An ancestor may destroy one of its ancestors, then bubbling will stop just before the destroyed ancestor without causing a problem. Note that the issuer of the command may can observe the changes made to the payload once the process is over, so ancestors can send data back to issuer.
Merge remote-tracking branch 'origin/dispatchToParents' into dispatchToParents