Bug 14305: View arbitrary branch's news, RSS fix

Bug 14305: View arbitrary branch's news, RSS fix

This fix changes the RSS link to reflect the URL paramter override.

This is less elegant than the existing solution which uses the
Branches TT module, perhaps there is a better way?

Sponsored-By: Halland County Library
Test plan:
* Follow instructions in the original patch but also check the
  URLs and contents of the RSS link at the bottom the OPAC page.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>