* Add support for proxy pass target options

* Add example usage

Removing the file /etc/apache2/sites-available/000-default.conf leads to an error when Apache is restarted.
So the symlink in /etc/apache2/sites-enabled/ should be removed, the actual file can stay.

Add gitignore, kitchen-ci files
Add some tests and documentation

- This is then ignored by Apache

Correct handling of allow encoded slashes

This is done by split the interface pillar value instead of using a proper
list so it behaves exactly the same as before for simple 1 interface cases
(no need to refactor one's pillar files).

The resulting is something like:

  Listen 1.2.3.4:80
  Listen [2001:abc:def:100::3]:80

  <VirtualHost 1.2.3.4:80 [2001:abc:def:100::3]:80>
  ...

Apache2 docs state this is global, but vhost overrides it even when not specified.

additionally, this directive is defaulted differently across distributions (eg. CentOS is default 'On')

this change allows control of the directive.

Sometimes it's necessary optimization in nginx+apache2 environment

Added example shows 503 code instead of "It works!" page.

By reassigning options with `blockreplace` at `/etc/apache2/conf-available/security.conf`, which is linked as conf-enabled by default on Debian packages

Add `onlyif` check to execute `a2dissite` only when needed.