Added FeedSync WP All Import Filter

/**
 * REAXML Address Sub Number field for title import 
 * processing Function for WP All Import and FeedSync
 *
 * This function adds a / after the $value else returns false. 
 * Usage in WP All Import Post Date field is: 
 * [epl_feedsync_filter_sub_number({address[1]/subNumber[1]})]
 * 
 * @since 1.3
 * @return formatted sub number/
 */