Update multivdu VNF descriptor to use ubuntu16.04 image instead of US1604

Update VNF descriptor to use ubuntu16.04 image instead of US1604 and add clout-init to set ubuntu password

hackfest_multivdu_vnf/hackfest_multivdu_vnfd.yaml

@@ -21,7 +21,7 @@ vnfd-catalog:
         vdu:
         -   id: mgmtVM
             name: mgmtVM
-            image: US1604
+            image: ubuntu16.04
             count: 1
             vm-flavor:
                 vcpu-count: 1
@@ -44,7 +44,7 @@ vnfd-catalog:
             -   id: mgmtVM-internal
         -   id: dataVM
             name: dataVM
-            image: US1604
+            image: ubuntu16.04
             count: 1
             vm-flavor:
                 vcpu-count: 1