LP1893968 SIP2 checkin-with-cancel / checkin API

LP1893968 SIP2 checkin-with-cancel / checkin API

Adds new option to open-ils.circ.checkin API called
"revert_hold_fulfillment".  It behaves much like a No-Op checkin, with
the addition that if a hold was fulfilled by the checked out item for
the patron which circulated the item, the hold fulfillment is rolled
back and the item is put back on the holds shelf.

Teaches the SIP Checkin code to pass the 'revert_hold_fulfillment' flag
to its checkin call when the SIP 'cancel' value is set, i.e. the SIP
'BI' field contains a 'Y' value.

Signed-off-by: Bill Erickson <berickxx@gmail.com>