In acq.fund_transfer: drop the NOT NULL constraint from dest_fund and

In acq.fund_transfer: drop the NOT NULL constraint from dest_fund and
dest_amount, in order to accommodate deallocations -- where we move
money out of a fund without moving it into another fund.

This change was applied via upgrade script # 0135, but apparently was
never applied to the base installation script.

M    Open-ILS/src/sql/Pg/200.schema.acq.sql

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_0@17885 dcc99617-32d9-48b4-a31d-7c20da2025e4