mod_invites_register: Fix missing 'from' attribute (thanks Martin) This should probably cause a noisier error in Prosody, than the current > No hosts[from_host] (please report): <stanza> A stack trace would have been useful, for example.

---
summary: Log a message once per minute
...

This module sends `-- MARK --` to the log once per minute. This may be
useful to give a sense of how busy the server is or see that logging and
timers are still working.