Correct special-casing of z-push Apache configuration

Writing clarifies thinking and leaves behind guidance for future
maintainers.  Design descriptions shouldn't be required, though,
especially for trivial modules.

Users expect role authors to make decisions.  The role author is
supposed to be the expert who knows what choices to make on behalf of
the user.

I probably got this wrong, but I'm putting a stake in the ground based
on work I've done on the Roundcube module and adding Let's Encrypt
support to the common module.

Conflicts:
	CONTRIBUTING.md

see: http://undeadly.org/cgi?action=article&sid=2016011414

resolves #453

Conflicts:
	roles/common/tasks/ufw.yml

Change default network buffer size
Should increase tcp tunnel speed for openvpn < 2.3.9
https://community.openvpn.net/openvpn/ticket/461

Per discussion on #429 (after the merge). This project is about encouraging users to run services themselves and not rely on for-profit corporations such as Google.

Fixes #406

add additional comment about `tun-mtu` parameter in openvpn config template

- google dns setting for client
- verb level
- mtu
- TLS settings

Notes about security: https://blog.g3rt.nl/openvpn-security-tips.html
Check privacy: http://witch.valdikss.org.ru/

because why the fuck not?

Thanks-to: 8e693b3db3

Conflicts:
	roles/common/tasks/main.yml

I ran a check on http://mail-tester.com and found out I was missing a header to be set for DMARC. SInce I missed it, maybe someone else missed it as well, so maybe it could go into the README.

Z-push apache config: Jessie also uses conf-available/conf-enabled

This reverts commit 6b53da4bdc.

Using a different approach to maintain wheezy compatibility

Jessie