Enable update_db.sh to handle upgrading databases with release version

Enable update_db.sh to handle upgrading databases with release version

When '0475' is mixed with '1.6.0.4', the latter wins as far as a plain MAX()
operator goes. Ensuring that the version is all digits should help avoid the
release version numbers in the config.upgrade_log table.

Thanks to Thomas Berezansky for suggesting a SIMILAR TO operator variation
that led to this approach.

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_1@19838 dcc99617-32d9-48b4-a31d-7c20da2025e4