Fix missing argument and topic title

* Fixed missing argument
* Fixed another bug with the custom title not being used for new topic notifications

This should also be fine with https://bbpress.trac.wordpress.org/ticket/2620 if nothing major changes there.

This should fix https://github.com/pippinsplugins/bbPress-Custom-Reply-Notifications/issues/4
Merge pull request #5 from ntwb/patch-1

Fix missing argument and topic title