Bug 7338: Follow up: show link only when there is more than 1 subscription

Bug 7338: Follow up: show link only when there is more than 1 subscription

To be tested together with
http://bugs.koha-community.org/bugzilla3/attachment.cgi?id=6690

1) Create a subscription for a title
- check the link 'Show any subscription...' doesn't show now
- check the serials collection page works correctly and shows all
necessary information

2) Create a second subscription for the same title
- check a new link 'Show any subscription...' shows up now
- use links in the issue table to change between viewing the single subscription
and the overview page
- check it works correctly and all information shows up

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
It works. With this patch, on Serials Collection page, the link, 'See any
subscription attached to this biblio' appears only when there are more than one
subscription attached to the biblio record.
(cherry picked from commit 42265ef21758acd6e44eca3a48ab57529628717c)

Signed-off-by: Chris Nighswonger <chris.nighswonger@gmail.com>