LP#1401177: uniquify attrs across a metarecord

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>
LP#1401177: Stamping upgrade script of unique_mr_attrs.sql.

Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>