Bug 14882: Librarians are not warned if patron owe more than maxoutstanding when...

If a patron owes more than the system preference maxoutstanding in fees
and fines, the patron will be unable to place holds via the opac.
However, a librarian placing a hold for a patron is not even warned!

Test Plan:
1) Apply this patch
2) Set maxoutstanding to 1.00
3) Find a patron owing more than 1.00
4) Attempt to place a hold
5) Note the warning that the patron owes money

Works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>