Introduce jacoco code coverage.
Shift jacoco config into plugin management of parent.
Remove reference to emma plugin.

Emma is replaced by jacoco.
Declare jaxb plugin in plugin managment of parent pom.
Declare build-helper-maven-plugin in plugin management section of the parent pom.
Added findbugs
Fix FindBugs message.
Fix unneeded import.
Refactor: get buildDir once from the maven project instead multiple times
Check return value of File#mkdirs
Improve mkdirs: throw exception when the file already exists but is not a dir.
Use FileUtils.mkdirs
Check return value of File#delete().
Improve performance: use entrySet
performanceImprovement: use Integer.valueOf instead of using constructor.
Throw exception if the parent folder of the sybolic link could not created.
Use FileUtils.mkdirs()
Ensure that stream is closed.
Use FileUtils.mkdirs().
Simplify null check.