LP#1160343: remove unused open-ils.circ settings

The circ_modifier and billing_types lists in the
open-ils.circ section of opensrf.xml are no longer
used.  This commit removes them from the opensrf.xml
example config.  It also removes the method
open-ils.circ.billing_type.retrieve.all, which has
not be used by any other code once in-DB billing types
were introduced.

Any external clients that used the method that was
removed should instead use
open-ils.circ.billing_type.ranged.retrieve.all.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Bill Erickson <berick@esilibrary.com>