Work-around for ownCloud 8.1.1 upgrade bug and tweaking munin's setup.

v0.13a (August 23, 2015)
------------------------

Note: v0.13 (no 'a', August 19, 2015) was pulled immediately due to an ownCloud bug that prevented upgrades. v0.13a works around that problem.

Mail:

* Outbound mail headers (the Recieved: header) are tweaked to possibly improve deliverability.
* Some MIME messages would hang Roundcube due to a missing package.
* The users permitted to send as an alias can now be different from where an alias forwards to.

DNS:

* The secondary nameservers option in the control panel now accepts more than one nameserver and a special xfr:IP format to specify zone-transfer-only IP addresses.
* A TLSA record is added for HTTPS for DNSSEC-aware clients that support it.

System:

* Backups can now be turned off, or stored in Amazon S3, through new control panel options.
* Munin was not working on machines confused about their hostname and had lots of errors related to PANGO, NTP peers and network interfaces that were not up.
* ownCloud updated to version 8.1.1 (with upgrade work-around), its memcached caching enabled.
* When upgrading, network checks like blocked port 25 are now skipped.
* Tweaks to the intrusion detection rules for IMAP.
* Mail-in-a-Box's setup is a lot quieter, hiding lots of irrelevant messages.

Control panel:

* SSL certificate checks were failing on OVH/OpenVZ servers due to missing /dev/stdin.
* Improve the sort order of the domains in the status checks.
* Some links in the control panel were only working in Chrome.