Bug 31038: Fix price formating in cashup summary

Bug 31038: Fix price formating in cashup summary

This patch uses the existing format_price JS include to format prices in
the cashup summary modal

Test plan
1) Create some transactions and a cashup
2) View the cashup summary modal and confirm amounts are not nicely
   formatted
3) Apply patch
4) Confirm amounts in cashup summary modals are now nicely formatted

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>