Bug 17834: Change library news text for single-branch libraries

Bug 17834: Change library news text for single-branch libraries

To test:
1) Log into OPAC, go to home page
2) Confirm that the text shows as 'RSS feed for (branchname) library
news' if single-branch library
3) Confirm text shows as normal for libraries with more than one branch

Sponsored-by: Catalyst IT
Signed-off-by: maricris <mlabancia@gmail.com>
Signed-off-by: anafe <anafeazuela@yahoo.com>
Signed-off-by: iflora <iflora@unimas.my>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 1417f83e8b8a57e70e9120244a36204cf4acb3c2)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>