Upgrade maven-findbugs to 2.5.2.

Also, delete the exclusions file. We're going clean from here on out.

Finally, drop Checkstyle. If it doesn't fail the build it doesn't exist.
Upgrade maven-gpg to 1.4.
Upgrade maven-compiler to 3.0.
Upgrade maven-surefire to 2.14.
Upgrade maven-source to 2.2.1.
Upgrade maven-javadoc to 2.9.
Upgrade maven-release to 2.4.1.
Upgrade maven-site to 3.2.
Upgrade maven-project-info-reports to 2.6.
Upgrade wagon-ssh to 2.4.