pom.xml: move mvn test plugin into the pluginManagement section
pom.xml: move mvn test plugin into the pluginManagement section

There is no top level tests to be run.

Signed-off-by: Pierre-Alexandre Meyer <ff019a5748a52b5641624af88a54a2f0e46a9fb5@ning.com>

pierre/serialization,pierre/serialization