Noissue - Fixed: Remember filter lists added by update attempt

I found that when you're adding a non-recommended filter list via the options page (i.e. either using a subscribe link or the "Add a new filter list" button), it would show up under More Filters twice - once for the "disabled" message and another time for the "added" message. The reason for that is that we're not adding them to subscriptionsMap when calling updateSubscription() instead of addSubscription(). This means that the second time we attempt to update the filter list we don't know that it has already been added and therefore add it again.