Move rsyslog preferences snippet to site_apt::preferences::rsyslog, to
group it with the other preferences snippets

Change-Id: I83928c6b82cd6218a80c95475729cb57f146ff85
Install wheezy-backports version of unbound, this is necessary to solve #2328

Change-Id: Ie28de8d3f7a8c8cf52ce30365379a476d48dc88b
lint cleanup of site_config::caching_resolver

Change-Id: I3f6a4db26e064a520a08822cf23fc3288b31af62
Implement #2328: unbound.conf: content changed on every puppetrun

This is done by using the include glob capability that is in the
wheezy-backports and newer unbound to include the
/etc/unbound/unbound.conf.d/* config files.

To do this, we need to transition from our /etc/unbound/conf.d directory
structure to use the one that the debian package uses.

This allows us to clean up the rather ugly way we were configuring the
resolver before.

Change-Id: I68347922f265bbd0ddf11d59d8574a612a7bd82c