Correct search opt param in SessionList

There are differences between session and other tables(
job, atcion, backup, client):
for example:
--search '{"match": [{"id": "820e30c284fb4d"}]}'
1.It is coversed to '{"match": [{"id": "820e30c284fb4d"}]}'
  in session
2.It is coversed to {'match': [{'_all': '{"match":
  [{"id": "820e30c284fb4d"}]}}]}' in other talbes
It can lead to mistakes:
ERROR freezer-api   File "/opt/stack/freezer-api/freezer_api/
storage/elasticv2.py", line 47, in get_base_search_filter
ERROR freezer-api     match_list = [{"match": m} for m
in search.get('match', [])]
 ERROR freezer-api AttributeError: 'unicode' object
 has no attribute 'get'
Change-Id: Id9b918208caef1f3b6d31e780a951b0ab6f5e98f

freezerclient/v1/sessions.py

@@ -100,10 +100,11 @@ class SessionList(lister.Lister):
         return parser
 
     def take_action(self, parsed_args):
+        search = utils.prepare_search(parsed_args.search)
         sessions = self.app.client.sessions.list_all(
             limit=parsed_args.limit,
             offset=parsed_args.offset,
-            search=parsed_args.search
+            search=search
         )
 
         # Print empty table if no sessions found

freezerclient/v2/sessions.py

@@ -102,10 +102,11 @@ class SessionList(lister.Lister):
         return parser
 
     def take_action(self, parsed_args):
+        search = utils.prepare_search(parsed_args.search)
         sessions = self.app.client.sessions.list_all(
             limit=parsed_args.limit,
             offset=parsed_args.offset,
-            search=parsed_args.search
+            search=search
         )
 
         # Print empty table if no sessions found