Resolve "symbiosis-crontab --test doesn't seem to work?"

Closes #77

See merge request !50

The iteration now moves the time on the the start of the next
hour/day/month as appropirate.

When generating manpages, we should test to make sure they're not empty.

See merge request !44

Resolve "exim4: Allow pipe-transport failures to queue messages"

Closes #71

See merge request !42

Also add blank line to end of 40-address-pipe to keep consistency with
other snippets.

If the executed program fails then don't return the output to the
sender as a bounce, instead keep the message queued.

Updated changelogs for pending jessie update

See merge request !33

autotest: Added new dev repo locations for testing

See merge request !19

Add full Gitlab CI

See merge request !18

This reverts commit 82298450.

Also fix up the DKIM test to reset the hostname if it thinks it is
localhost, as this is explicitly disallowed in the code (for some
reason).

This allows hosts with duff hostnames (without dots) to run tests,
assuming the env variable HOSTNAME is set.

Looking at you, Docker.

This reverts commit dc3692ea.

Not sure this is a good idea, but it might make the tests pass..