Bug 11647: (follow-up) test if user is logged in before proposing to subscribe or...

Bug 11647: (follow-up) test if user is logged in before proposing to subscribe or unsubcribe from serial routing list

To test :
1) Search for a subscription with patron notification active
2) If you're not logged in, a message warns you that you must log
   in to subscribe to notification on new issues
3) If you log in, and have not yet subscribed to this routing list,
   you've got a link to subscribe
4) Once you have subscribed, you've got a link to unsubscribe
5) If you log out, you've got a message saying you must log in to
   subscribe
6) If you log in with another user, you've got the link to subscribe
   or unsubscribe depending on if he has already subscribed.

Signed-off-by: remy juliette <remy.gonzalves@iepg.fr>
Signed-off-by: Aurelie Fichot <aurelie.fichot@iepg.fr>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit b056f93c4d33a9a56d56bbb081924f7c4c974a79)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>