Bug 28728: Link to holds page from holds raio

Bug 28728: Link to holds page from holds raio

To test:
1 - Find a bib with 1 item, place 3 bib-level holds on it (just to make
    sure there's at least one title on your holds ratio page)
2 - Go to the holds ratio page in circulation
3 - mouse over the Holds Ratio column, see that the number there is a
    link to http://[your koha]/cgi-bin/koha/circ/reserveratios.pl#, the
    page you're already on
4 - apply patch, restart_all, reload page
5 - link now goes to the holds page for that title

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>