Bug 23321: Add cash register support to paycollect

Bug 23321: Add cash register support to paycollect

This patch ties in the cash registers system to the paycollect payment
pages in the staff client.

Test plan:
1) Add some manual fees to a test patron
2) Select some fees to pay off
3) Note the addition of a select box for selecting your cash register
   upon payment.
4) Set a branch default cash register for the current branch
5) Repeat step 3 and note that the pre-selected cash register is the one
   set in step 4.
6) Unset the branch default cash register for the current branch
7) Repeat step 3 and note that there is no cash register pre-selected
8) Set 'UseCashRegisters' to 'Do not'
9) Repeat step 3 and note that there is no longer an option to select a
   cash register
10) Signoff

Sponsored-by: PTFS Europe
Sponsored-by: Cheshire Libraries Shared Services
Signed-off-by: Maryse Simard <maryse.simard@inlibro.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>