Fixing a javadoc issue on jdk6
Changing the Lucene/Solr depenendency to be 4.4
Bumped the version from 0.5.1 to 0.6.0.
Updated release notes for 0.6.0.
[maven-release-plugin] prepare release release-0.6.0
[maven-release-plugin] prepare for next development iteration
Update jdiff files.