SONA: OpenstackSwitching - remove flows

 - Remove the corresponding flows when VMs are removed.
 - Remove the IP mapping of the VM removed from the DHCP service (even when doNotPushFlows is true)
 - Updated the network config json file to reflect the change of cordvtn
Change-Id: I4c359d456422ece37b93e6366f2fd4daaf081a37
diff --git a/apps/openstackswitching/app/pom.xml b/apps/openstackswitching/app/pom.xml
index 7d26f8f..719b049 100644
--- a/apps/openstackswitching/app/pom.xml
+++ b/apps/openstackswitching/app/pom.xml
@@ -40,6 +40,9 @@
         </api.description>
         <api.package>org.onosproject.openstackswitching.web</api.package>
         <onos.app.origin>SKT, Inc.</onos.app.origin>
+        <onos.app.requires>
+            org.onosproject.dhcp
+        </onos.app.requires>
     </properties>