Fix for xmpp/sms notification options appearing to be disabled on new subscriptions.

Fix for xmpp/sms notification options appearing to be disabled on new subscriptions.
Base problem is that our caching-on-insert interferes with relying on column default values; the cached object is missing those fields, so they appear to be empty (null) when the object is retrieved from cache.
Now explicitly setting them when inserting subscriptions, and cleaned up some code that had alternate code paths.

May also have made auto-subscription work for remote OStatus subscribers, but can't test until magic sigs are working again.