Add NS and VNF package to test support of several volumes

Signed-off-by: garciadeblas gerardo.garciadeblas@telefonica.com

several_volumes_ns/several_volumes_nsd.yaml

+nsd:
+  nsd:
+  - description: NS with 1 VNFs connected to mgmtnet VL
+    df:
+    - id: default-df
+      vnf-profile:
+      - id: vnf-several-volumes
+        virtual-link-connectivity:
+        - constituent-cpd-id:
+          - constituent-base-element-id: vnf-several-volumes
+            constituent-cpd-id: vnf-mgmt-ext
+          virtual-link-profile-id: mgmtnet
+        vnfd-id: several_volumes-vnf
+    id: several_volumes-ns
+    name: several_volumes-ns
+    version: '1.0'
+    virtual-link-desc:
+    - id: mgmtnet
+      mgmt-network: true
+    vnfd-id:
+    - several_volumes-vnf