code: public List<WnsNotificationResponse> pushToast(List<String> channelUris, WnsToast toast) throws WnsException {
  		return this.pushToast(channelUris, null, toast);
  	}
docs: Pushes a toast to channelUris
  @param channelUris
  @param toast which should be built with {@link ar.com.fernandospr.wns.model.builders.WnsToastBuilder}
  @return list of WnsNotificationResponse for each channelUri, please see response headers from <a href="http://msdn.microsoft.com/en-us/library/windows/apps/hh465435.aspx#send_notification_response">http://msdn.microsoft.com/en-us/library/windows/apps/hh465435.aspx#send_notification_response</a>
  @throws WnsException when authentication fails