use pcrud auto-complete widget when selecting providers

use pcrud auto-complete widget when selecting providers

Fixes general slowness working with invoice and PO forms if
more than a couple hundred providers are defined.

This could be generalized with a bit of work with Fieldmapper
to define "has-one-chosen-by-user-from-cast-of-thousands"
relationships that should trigger use the auto-complete widget.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_0@18787 dcc99617-32d9-48b4-a31d-7c20da2025e4