Bug 36507: Allow non-superlibrarians to set desk and register

Bug 36507: Allow non-superlibrarians to set desk and register

To test:

1. Turn on UseCirculationDesks
2. Create some desks
3. Login as a non-superlibrarian
4. Try to switch desks, get an error

5. Turn on UseCashRegisters
6. Create some registers
7. As a non-superlibrarian try to change your register, get an error.

8. APPLY PATCH and restart_all
9. Try changing your desk and register again, it should now work.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>