Include maven findbugs plugin in pom.xml
Include maven findbugs plugin in pom.xml

This plugin performs some static code analysis and (hopefully) finds
obvious mistakes and bugs in our code. Just like the checkstyle plugin I
also added its `check` goal to the test phase.

stefanoberdoerfer/exmatrikulator,stefanoberdoerfer/exmatrikulator,stefanoberdoerfer/exmatrikulator,stefanoberdoerfer/exmatrikulator,stefanoberdoerfer/exmatrikulator