OGM-438 Introduce a helper to test Infinispan in clusterd mode


For @gmorling to handle, but good to go in _master_ :
 - https://hibernate.atlassian.net/browse/OGM-438

To be used as a Rule:

    @Rule
    public final InfinispanNode nodeA = new InfinispanNode( "nodeA", "infinispan-dist.xml" );
    @Rule
    public final InfinispanNode nodeB = new InfinispanNode( "nodeB", "infinispan-dist.xml" );

    @Test
    public void testMarshalling() throws Exception {
        EmbeddedCacheManager manager = nodeA.getCacheManager( 2 ); //Number of nodes this cluster should have
        ...