[Maven] Use version 2.8.1 of formatter-maven-plugin
[Maven] Use version 2.8.1 of formatter-maven-plugin

Version 2.8.1 is the last one that does not require
Maven version 3.3.9.

bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr