Bug 26272: Add ajax driven cashup modal to library page

Bug 26272: Add ajax driven cashup modal to library page

This patch adds an ajax driven cashup summary modal to the library
registers summary page.

Test plan
1/ Enable UseCashRegisters in the system preferences
2/ Add at least one cash register to your library
3/ Make some payments of various types (Cash, Card) against the cash
register
4/ View the register transactions details page
5/ Make a refund against a payment
6/ Cashup
7/ View the cashup summary by clicking on the 'Summary' link on the
register page.
8/ Navigate to the 'libraries' summary page
9/ View the cashup summary by clicking on the 'Summary' link in the
registers table.
10/ Signoff

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>