Bug 20187: New rewrite rules can break custom css

Bug 20187: New rewrite rules can break custom css

Koha has the ability to include custom css in the apache configuration.
If a library has any custom css ( or adds a custom js file in some way ),
and that file has an underscore in it ( e.g. my_custom.css ), the
apache rewrite rule will convert it to my.css and thus it will 404.

We should make the rewrite rules as specific as possible for the
format we are using.

Test Plan:
1) Set OPAC_CSS_OVERRIDE to a file with an underscore in it
2) Note it does not work
3) Apply this patch
4) Update the apache rewrite rules to match those in the patch
   For kohadevbox, just run /home/vagrant/misc4dev/cp_debian_files.pl
5) Restart apache
6) Reload the page, your custom css should load now!

Signed-off-by: Victor Grousset <victor.grousset@biblibre.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>