DERBY-6650: Parse Lucene versions leniently

Lucene 4.9 changed the format of version strings (from LUCENE_48 to
LUCENE_4_9). We need to recognize both in order to detect if an
upgrade has happened.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1609716 13f79535-47bb-0310-9956-ffa450edef68