Fix app-host exec handler arguments to match the spec.
Fix app-host exec handler arguments to match the spec.

- The arguments to the exec handler in app-host side
are the same arguments of the sim-host side exec calls:
success callback, fail callback and args.

TimBarham/cordova-simulate,busykai/cordova-simulate,Microsoft/taco-simulate-server,Microsoft/taco-simulate-server,TimBarham/cordova-simulate,busykai/cordova-simulate