Bug 10942: (follow-up) create a /etc/koha/koha-common.conf

Bug 10942: (follow-up) create a /etc/koha/koha-common.conf

This patch creates a new master configuration file for the
koha-common package, and moves the AUTOMATIC_TRANSLATIONS_UPDATE
variable rather than leaving in in /etc/default/koha, which is meant
to be used for init script settings.

The configuration format is simple - a shell script that
sets variables and which can sourced by another script or
trivially parsed.

To test:

- Apply the patch series for bug 10942 and build a package.
- Install the package.
- Verify that a new config file, /etc/koha/koha-common.conf.
- Follow the rest of the test plan for the main page (e.g.,
  set AUTOMATIC_TRANSLATIONS_UPDATE and force a package upgrade).

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Robin Sheat <robin@catalyst.net.nz>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>