Add SpotBugs and checkstyle to the pom files.

Currently we have a number of issues that Spotbugs will detect.  I ran a quick test this afternoon and it found 60 potential bugs.  This ticket is to add spotbugs to the maven build, ensure that no bugs are found and ensure that the build will fail if bugs are found.

Add checkbugs as well.

As most of the reported errors cannot be fixed with JDK8, add exclusions for these "old"/JDK8-classes that do not allow to set a proper encoding, thus relying on the default system encoding!