dc_clustering_SUITE: config to enable clustering, fixed bad match
dc_clustering_SUITE: config to enable clustering, fixed bad match

- the testsuite failed when dc_clustering was not enabled in the scalaris config file
- single_node/1 failed due to a bad match (return value of get_vivaldi_and_centroids/2
        changed)

l4u/scalaris-mirror,l4u/scalaris-mirror,l4u/scalaris-mirror,l4u/scalaris-mirror,l4u/scalaris-mirror,l4u/scalaris-mirror