Fix bug 1533: Update config for nscharm

(cherry picked from commit 4c5a1382)

nscharm_ns/charms/layers/ns/config.yaml

 options:
-    user-member-index:
-        default:
-        description: The vnf-member-index of the user VNF.
+    juju-username:
         type: string
-    user-vdu-id:
-        default:
-        description: The id of the VDU containing the charm.
+        default: ""
+        description: "The Juju username to authenticate with."
+    juju-password:
         type: string
-
-    policy-member-index:
-        default:
-        description: The vnf-member-index of the policy VNF.
-        type: string
-    policy-vdu-id:
-        default:
-        description: The id of the VDU containing the charm.
+        default: ""
+        description: "The Juju password to authenticate with."
+    ns_config_info:
         type: string
+        default: ""
+        description: "The NS_CONFIG_INFO containing the mapping of NS object to application names"