Added findbugs to maven

Maven will now fail if it finds findbugs problems.
I have added all the findbugs problems in the exclude file so we can build.
The idea is that the exclude file is going to be empty at the end of the
release.
Merge pull request #1796 from pveentjer/maven-findbugs

Added findbugs to maven
Resolved findbugs issue in wan package

When an replication event can't be published, it was dropped without giving any kind of logging warning.
Removed the wan package from findbugs exclusion