[ONOS-5708] Implement VirtualNetworkFlowRuleManager

Changes
1. VirtualFlowRuleStore is added
2. VirtualFlowRuleManager test code is added
3. VirtualProviders can be registered through VirtualNetworkManager
4. VirtualFlowRuleManager is implemented
5. VnetServiceWithProvider service is added for interconnectiong
    VirtualProvider and VirtualProviderService

TODO
1. Implement more test cases

Change-Id: I0a1ce633b8ed78f0529e40ed34ae702974f53f69
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/provider/AbstractVirtualProviderService.java b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/provider/AbstractVirtualProviderService.java
index e12f1ef..8603be5 100644
--- a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/provider/AbstractVirtualProviderService.java
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/provider/AbstractVirtualProviderService.java
@@ -25,7 +25,7 @@
  * @param <P> type of the information provider
  */
 public abstract class AbstractVirtualProviderService<P extends VirtualProvider>
-        implements VirtualProviderService {
+        implements VirtualProviderService<P> {
 
     private boolean isValid = true;
     private P provider = null;