fixes #206 (hopefully)

fixes #195

don't allow catch-all addresses in the admin because they take precedence over mail users and that's counter-intuitive

For now use the command-line tools/mail.py if you need it.

see #200

Revert "Changed incomming-email-input to type text"

This reverts commit 9631fab7.

see http://discourse.mailinabox.email/t/activesync-z-push-not-working/94/3

see https://discourse.mailinabox.email/t/set-www-a-and-other-dns-records-after-install/63/10

don't run `apt-get update` when generating the status checks output because it is so slow and should be update daily by cron anyway

https://discourse.mailinabox.email/t/opening-up-a-custom-port-for-ssh-after-install/55/2

revise the description of A records on domains: the A record must be present for good deliverability so that the envelope domain resolves, but it doesn't have to resolve to this machine

add link to contributors, remove duplicate "to"s

Changed incomming-email-input to type text

The input type="email" validation won't allow "@example.com", which is needed for catch-all-aliases.

update roundcube version

In the event the first user is an address that we'd normally create as an alias,
we'd generate a loop from the alias to the administrative alias to the first user
account (which was the alias again).

hopefully fixes #186

only hold onto backups for 14 days (not 31) and show when the backups will be deleted in the control panel

Since it runs before the real setup begins, we must make sure that packages are installed.

Also removing bind9-host's installation from system.sh. In 189dd600 I added this so we could use `host`
to aid Docker autoconfiguration. Docker support was since removed but this hadn't gotten removed, which lead me to think it was
normally installed by Ubuntu. It's now installed in `network-checks.sh`.

fixes #180

dns: move the quoting of TXT records to when we write the zone file so that we can display it unquoted in the External DNS instructions

Support more concurrent connections for PHP services