mod_http_muc_log: Fix exception on lack of trailing slash in room path A request to /room leads to the match call returning nil which in turn calls nodeprep(nil). In Prosody 0.11.x this does nothing and simply returns the nil, while in 0.12 it is an error. Now it redirects to the calendar view at /room/ - even for non-existant rooms. Discovered at a deployment with http_paths = { muc_log = "/" } and requests to /robots.txt and similar, which now result in a uses redirect before returning 404.

Generate a DNS UPDATE order in format suitable for `nsupdate` based on
current port configuration.

Example output:

```
$ prosodyctl mod_dnsupdate -d example.com -t xmpp.example.com example.com
zone example.com
server ns1.example.com
ttl 3600
add _xmpp-client._tcp.example.com IN SRV 1 1 5222
add _xmpp-server._tcp.example.com IN SRV 1 1 5269
```