Update some build tools

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1621540 13f79535-47bb-0310-9956-ffa450edef68
Update to Clover 4.0.0 (and update license)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1621543 13f79535-47bb-0310-9956-ffa450edef68