Update to latest versions of plugins
Remove DoubleCheckedLocking check as latest checkstyle does not support it

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/dbcp/trunk@1571824 13f79535-47bb-0310-9956-ffa450edef68
Start working on checkstyle errors

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/dbcp/trunk@1571825 13f79535-47bb-0310-9956-ffa450edef68