Add example of a cassandra daemonset.

Introduce examples explaining how to use DataSets to optimally
distribute cassandra nodes onto each kubernetes node in the network.

Signed-off-by: Christian Stewart <christian@paral.in>

examples/examples_test.go

@@ -244,6 +244,7 @@ func TestExampleObjectSchemas(t *testing.T) {
 			"rbd-with-secret": &api.Pod{},
 		},
 		"../examples/cassandra": {
+			"cassandra-daemonset":  &extensions.DaemonSet{},
 			"cassandra-controller": &api.ReplicationController{},
 			"cassandra-service":    &api.Service{},
 			"cassandra":            &api.Pod{},