add(tarsnap): Script to rotate backups

fix(gitignore): absolute path for user.yml file

.gitignore contained complete path to /vars/user.yml but we want to ignore the
locale version inside local vars directory

add(apticron): configure email

add(fail2ban): Add server IP address to ignore IP

Apticron is configured to send email to {{ admin_email }}

ignoreip field inside /etc/fail2ban/jail.local is populated with
server_ip_address variable

Add tasks to install script/tarsnap configuration file and a cronjob to run
the backup job
Number of hourly/daily/weekly/monthly backups kept can be configure from the
tarsnap.sh script

Thanks to this script, we don't use all the backups which save space on
tarsnap server and thus reduce the price to pay

Don't open unused ports

Sovereign does not currently use jabber/xmpp or insecure smtp.

Skip a2enmod and a2ensite tasks if not required

Tell the user to use Vagrant 1.3.x

Set two variable files from site.yml

Apache vhost misconfiguration

Tarsnap warns about leading /

That way it's more convenient to uncomment an entire paragraph.

Refs #39

That way the default values will not be applied by mistake. The user
needs to uncomment the lines from `vars/users.yml` and set them.

Also renamed openvpn variables.

Refs #39

Refs #39

That way we can override all the config from a central location. The
`user.yml` file overrides `defaults.yml`. `user.yml` was added to
`.gitignore` in order to allow a user to change it without having to
worry about merges. It's easy to do a diff to see what changed between
the defaults and your own settings.

Needs documentation, this is just a proposal.

Refs #39

Fix trailing whitespace

Also replace the global variable with a local one

(such as root's cron errors)

Feature/roundcube

TLS fixes & detailed install instructions

Fix CAcert usage in postfix and dovecot

Fix Postfix TLS configuration

Fix Postfix configuration file to link to correct SSL certificate locations