Build on Java 7 & 8

Signed-off-by: Sebastian Hoß <mail@shoss.de>
Only build an Java 8

Signed-off-by: Sebastian Hoß <mail@shoss.de>
Use latest java-parent

Signed-off-by: Sebastian Hoß <mail@shoss.de>
[maven-release-plugin] rollback the release of suppress-warnings-1.0.1