Bug 10848 - Allow configuration of mandatory/required fields on the suggestion form...

Bug 10848 - Allow configuration of mandatory/required fields on the suggestion form in OPAC

This patch adds a configuration option which allows to define which
fields should be mandatory for a patron purchase suggestion form in OPAC.

Test plan:

1/ Apply patch.
2/ Play with the new OPACSuggestionMandatoryFields system preference
(select some fields as manadatory, select all, deselect all, try to
submit some suggestions with mandatory fields filled and/or not
filled etc.) to ensure that required fields (and only required fields)
are enforced in the browser to be filled.
3/ With all options deselected, 'Title' field should still be
mandatory (by default).

Signed-off-by: barbara johnson <barbara.johnson@bedfordtx.gov>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>