Renamed *Instance to *Node for better readability and to avoid conflict with notion of Karaf instance.
Added cluster service and trivial store implementations.
diff --git a/core/api/src/main/java/org/onlab/onos/net/link/LinkStore.java b/core/api/src/main/java/org/onlab/onos/net/link/LinkStore.java
index 4391471..dbe4877 100644
--- a/core/api/src/main/java/org/onlab/onos/net/link/LinkStore.java
+++ b/core/api/src/main/java/org/onlab/onos/net/link/LinkStore.java
@@ -8,8 +8,7 @@
 import java.util.Set;
 
 /**
- * Manages inventory of infrastructure links. It may do so using whatever
- * means are appropriate.
+ * Manages inventory of infrastructure links; not intended for direct use.
  */
 public interface LinkStore {