Started to work on topology abstraction.
Added more unit tests.
Changed mastership application to be synchronous.
diff --git a/net/api/src/test/java/org/onlab/onos/net/DefaultLinkTest.java b/net/api/src/test/java/org/onlab/onos/net/DefaultLinkTest.java
index 37757af..ec8511e 100644
--- a/net/api/src/test/java/org/onlab/onos/net/DefaultLinkTest.java
+++ b/net/api/src/test/java/org/onlab/onos/net/DefaultLinkTest.java
@@ -21,7 +21,7 @@
     private static final PortNumber P1 = portNumber(1);
     private static final PortNumber P2 = portNumber(2);
 
-    public static ConnectPoint cp(DeviceId id, PortNumber pn) {
+    public static ConnectPoint cp(ElementId id, PortNumber pn) {
         return new ConnectPoint(id, pn);
     }