Fix #799 (prevent multiple events for touchdevices)
see http://www.html5rocks.com/en/mobile/touchandmouse/?redirect_from_locale=de
see http://stackoverflow.com/questions/13655919/how-to-bind-both-mousedown-and-touchstart-but-not-respond-to-both-android-jqu
Merge pull request #807 from maihacke/master

Fix #799 (prevent multiple events for touchdevices)