broken by b30d7ad8 when the API began to list both real users and archived mailboxes in the JSON response

when deleting my old /usr/local/bin/mailinabox-exchange-autodiscover.php file from existing systems, don't emit an error if the file doesn't exist (added -f)

The secret key that encrypts the backups should not be world readable.

Works like this:

```curl -d "" --user email:password https://.../admin/dns/set/qname/rtype/value```

where the rtype and value default to "A" and the remote IP address of the request, so that a simple, empty POST to

```https://.../admin/dns/set/desktop.mydomain.com```

will point desktop.mydomain.com to the caller's IPv4 address.

closes #140

Move this into system.sh rather than anagement.sh.

This reverts commit eab28c97.

https://github.com/mail-in-a-box/mailinabox/pull/150#issuecomment-53120156

Read timezone from /etc/timezone.

Typo in introduction "later later"

short_open_tag=Off was mistakenly left in the earlier merge (was a fix for my old autodiscover.php but not needed with z-push), also regrouping the nginx directive to be near the rest of Z-Push

z-push autodiscover should use the primary hostname for the mail server and not the domain part of the email address (both may work, but the primary hostname is more likely to have a signed SSL cert)

* zen.spamhaus.org
* dbl.spamhaus.org
* checks if a connection to Google's MTA on port 25 works

broken in 04454b35

fixes #143

closes #19

whats_next: when there are multiple responses like for NS records sort the responses so we can compare to a fixed order

Merges branch 'owncloud' of github.com:jkaberg/mailinabox
which is pull request #135, closes #135

thanks @jkaberg, @fmbiete, @owncloud