Bug 22588: Simplify getting fines information in opac and selfcheckout

Bug 22588: Simplify getting fines information in opac and selfcheckout

Test plan:
0) Have patron with some fines and credits
1) Go to opac and log in
2) Go to 'your summary' page and confirm it shows the right amount and
description for both, credit and debit
3) Go to 'your fines' page and confirm it show right information
4) Go to self checkout page and confirm the fines are right here

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>