- Add PMD report.
- findbugs-maven-plugin 2.5.2 -> 2.5.3.
- cobertura-maven-plugin 2.0 -> 2.6.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/exec/trunk@1553828 13f79535-47bb-0310-9956-ffa450edef68