* Don't issue a write query to the database if the wl_notificationtimestamp is alread...

* Don't issue a write query to the database if the wl_notificationtimestamp is already null, so we don't to do at COMMIT et al. on every view request on an user watching the page
* Made WatchedItem select wl_notificationtimestamp instead of "1"
* Added loading mechanism, accessor to wl_notificationtimestamp and method to reset that timestamp