Bug 23321: Allow setting of branch default

Bug 23321: Allow setting of branch default

This adds the ability to set a cash register as the default selected
option when making payments at a particular branch.

1) Note the addition of a 'Make branch default' button in each row of
   the table under 'Manage cash registers'
2) Click the button and note that the button has changed.
3) Click on an alternative cash register for the same branch and note
   that the default has been switched to the new register.
4) Click the 'unset' button on the default branch and note that there is
   no longer a default register for this branch.
5) 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>