pg-migrator - pg_migrator: Support new backend API to preserve

Log Message:
-----------
Support new backend API to preserve relfilenodes, avoiding complex toast
renaming for 8.5.

Modified Files:
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pg_migrator:
INSTALL.jp (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pg-migrator/pg_migrator/INSTALL.jp?r1=1.5&r2=1.6)