Enabling Pylint in RO and removing unused methods

Enabling pylint, removing some unused and erroneous methods,
updating required libraries.

Change-Id: I7ad823f83faa1fd9f055a92041cabc7a53f707ac
Signed-off-by: Gulsum Atici <gulsum.atici@canonical.com>
diff --git a/NG-RO/osm_ng_ro/ns_thread.py b/NG-RO/osm_ng_ro/ns_thread.py
index ed971dc..6e94956 100644
--- a/NG-RO/osm_ng_ro/ns_thread.py
+++ b/NG-RO/osm_ng_ro/ns_thread.py
@@ -1791,9 +1791,9 @@
         )
         plugin_name = ""
         vim = None
+        step = "Getting {}={} from db".format(target, _id)
 
         try:
-            step = "Getting {}={} from db".format(target, _id)
             # TODO process for wim, sdnc, ...
             vim = self.db.get_one(target_database, {"_id": _id})