Use postmaster@ for DMARC reports

Switching to Ansible 2

* Install Python 3 pip and cgit dependencies
* Update to cgit 1.1
* Correct Ansible tag syntax for recent versions of Ansible

Avoid opportunity for copy-paste trouble

Also more scriptable, in vein of alternative commands provided

Ensure en_US.UTF-8 locale is present

Update README.md

Correct command line

#626 configure dovecot to move spam to junk folder

Clarifies environments, adds non-passwordless option

It was unclear where do to the commands. Not everyone will know ansible should not be run from the server. Also, the "optional" passwordless option was not actually optional, given how this was written.

Syntax fix in vpn and xmpp tasks.

Add antispam plugin config for dovecot to trigger rspamd learning whe…

Enable ownCloud virtual host automatically

Bump selfoss_version

Fix mail_virtual_domains config reading in opendkim

without this change it fails on ansible(2.2.0.0) with the following message:

    TASK [mailserver : Generate OpenDKIM keys] *************************************
    fatal: [sovereign.host]: FAILED! => {"failed": true, "msg": "the field 'args' has an invalid value, which appears to include a variable that is undefined. The error was: 'unicode object' has no attribute 'name'\n\nThe error appears to have been in '/Users/nfedyashev/Projects/sovereign/roles/mailserver/tasks/opendkim.yml': line 19, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n- name: Generate OpenDKIM keys\n  ^ here\n"}

Fix bare variable depreciation

Newer versions of Ansible complain when using bare variables like
`mail_virtual_users` and prefer the newer `'{{ mail_virtual_users }}'`
syntax.

Noticed the depreciation warning with Ansible version 2.1.2.0.

Update readme ubication of passwords

The debian81 image used before is no longer available.

The directory `/decrypted/roundcube` is not writeable by the user
`www-data`.  This leads to "unable to connect to the database" errors
from roundcube on new installs.  This patch corrects the problem.

Use a Unix socket instead of a TCP socket as a Unix socket doesn't play nicely with postfix running
smtpd in a chroot. The author of rmilter recommends using a TCP socket per
https://github.com/vstakhov/rmilter/issues/39

Changelog at https://github.com/SSilence/selfoss/releases/tag/2.15

Setup postgres in common role

Added abuse as a default alias
It's mentioned in RFC 2142, I think it'll do no harm to add this

Postgres is used by several roles, but the setup is currently part of the 'mailserver' role. By moving it to 'common', it's possible to disable the mailserver without breaking the others.