Bug 7234: koha-common Debian package now includes koha-sites.conf

This patch adds a sample koha-sites.conf file, which will be
included by the koha-common package in /etc/koha (where it belongs).

It is fixed to include the current defaults (DOM indexing for both
biblios and authorities, disabled use of memcached, and good defaults
for a normal setup if enabled).

All options are commented for ease of use by average users.

To test
- verify that the defaults are sane (let me know if it needs to be
  fixed).
- build the package and verify that the file gets installed.

Sponsored-by: Universidad Nacional de Cordoba

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Robin Sheat <robin@catalyst.net.nz>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 9ca12df4a006901b1f4710f364e3acc0259e46a1)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>