[ONOS-5731] Implement skeleton of VirtualNetworkPacketManager

Changes
1. Added VirtualNetworkPacketManager
2. Added VirtualNetworkPacketStore interface and impl class
3. Added VirtualPacketStore impl
4. Simple test cases are added

Todo
1. More test cases

Change-Id: I86f0484a9ee038dab8716703f0e5e41cbcf30cb1
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/AbstractVnetService.java b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/AbstractVnetService.java
index 2eac0af..3700e28 100644
--- a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/AbstractVnetService.java
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/AbstractVnetService.java
@@ -16,7 +16,6 @@
 
 package org.onosproject.incubator.net.virtual;
 
-import org.onlab.osgi.DefaultServiceDirectory;
 import org.onlab.osgi.ServiceDirectory;
 
 import static com.google.common.base.Preconditions.checkNotNull;
@@ -38,7 +37,7 @@
         checkNotNull(networkId, NETWORK_NULL);
         this.manager = manager;
         this.networkId = networkId;
-        this.serviceDirectory = new DefaultServiceDirectory();
+        this.serviceDirectory = manager.getServiceDirectory();
     }
 
     @Override