DERBY-590: Add backup/restore support for Lucene indexes and prevent the Lucene plugin from being used in an encrypted database; commit derby-590-26-ad-backupRestoreEncryption.diff.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1591910 13f79535-47bb-0310-9956-ffa450edef68