Bug 7567 - Added branchcode to opac_news

Bug 7567 - Added branchcode to opac_news

This patch merely adds branchcode varchar(10) DEFAULT NULL to
the opac_news table.

TEST PLAN
---------
 1) backup your kohadata base if you care about the data.
 2) use the koha database
 3) describe opac_news;
 4) show create table opac_news;
    -- No branchcode constraint will exist.
 5) apply the patch
 6) upgrade the database (either staff client or script)
 7) use the koha database
 8) describe opac_news;
 9) show create table opac_news;
    -- The branchcode constraint should be listed.
10) drop that koha database
11) create the koha database
12) use the koha database
13) source ~/kohaclone/installer/data/mysql/kohastructure.sql
    -- there should be no errors in creating the database.
14) describe opac_news;
15) show create table opac_news;
    -- The branchcode constraint should be listed.
16) restore your koha database if you backed it up.

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>