message: Changed to accept falsey
  Only add on before listener if you want to cancel so reasonable to expect a boolean return
diff: @@ -135,7 +135,7 @@ class StateNavigator {
  var { state, data } = this.stateHandler.parseLink(url);
  for (var id in this.onBeforeNavigateCache.handlers) {
  var handler = this.onBeforeNavigateCache.handlers[id];
  - if (oldUrl !== this.stateContext.url || handler(this.stateContext.state, state, data, url) === false)
  + if (oldUrl !== this.stateContext.url || !handler(this.stateContext.state, state, data, url))
  return;
  }
  var navigateContinuation = this.getNavigateContinuation(oldUrl, state, data, url, historyAction, history);
  