Bug 18026: Correct URL to database columns from .pref files

Bug 18026: Correct URL to database columns from .pref files

Recently the DB schema website has been updated.
The link to the columns' tables is now
  http://schema.koha-community.org/master/tables/table.html
  http://schema.koha-community.org/16_11/tables/table.html
  http://schema.koha-community.org/16_05/tables/table.html
instead of
  http://schema.koha-community.org/tables/table.html

To have a specific schema per Koha version.

To avoid fixing this link every release this patch adds a __VERSION__
marker to replace with the $version if stable ($version % 2) or 'master'

Test plan:
On master, 16.11.x and 16.05.x
Search for PatronSelfRegistrationBorrowerUnwantedField,
BorrowerMandatoryField and UniqueItemFields
Click on the link
You should get the correct page

This patch WILL NOT WORK on 3.22.x

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>