DERBY-6617: Stabilize MissingPermissionsTest

Make sure the ij process is shut down cleanly to make the exit code stable.

Use a regular expression to check for messages in the test output. The
regular expression accepts both double-quoted and unquoted names, and
any directory separator, to account for platform differences.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1610662 13f79535-47bb-0310-9956-ffa450edef68