Started to work on topology abstraction.
Added more unit tests.
Changed mastership application to be synchronous.
diff --git a/net/api/src/main/java/org/onlab/onos/net/topology/LinkWeight.java b/net/api/src/main/java/org/onlab/onos/net/topology/LinkWeight.java
new file mode 100644
index 0000000..89ef577
--- /dev/null
+++ b/net/api/src/main/java/org/onlab/onos/net/topology/LinkWeight.java
@@ -0,0 +1,10 @@
+package org.onlab.onos.net.topology;
+
+import org.onlab.graph.EdgeWeight;
+
+/**
+ * Entity capable of determining cost or weight of a specified topology
+ * graph edge.
+ */
+public interface LinkWeight extends EdgeWeight<TopoVertex, TopoEdge> {
+}