Implement XEP-0198 revision 1.5.2 and limit number of hibernated sessions per user Revision 1.5.2 allows sending h-values on resumes that fail due to hibernation timeout and to send out a smacks ack directly before the stream close tag. I also made the used timers stoppable even for prosody 0.10 and below, this makes the smacks-ack-delayed event more useful.

This module adds a command to `prosodyctl` for listing users.

``` sh
prosodyctl mod_listusers
```