Apply some fixes that were earlier applied to the base installation script

Apply some fixes that were earlier applied to the base installation script
090.schema.action.sql, but not in an upgrade script.

Also: correct a typo (INTEVAL -> INTERVAL).  Hence this upgrade needs to go
to v2.0 as well as to trunk.

M    Open-ILS/src/sql/Pg/090.schema.action.sql
M    Open-ILS/src/sql/Pg/002.schema.config.sql
A    Open-ILS/src/sql/Pg/upgrade/0418.function.action.fix-purge-circ.sql

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_0@17943 dcc99617-32d9-48b4-a31d-7c20da2025e4