Remove thin methods which is not used

Due to recent changes in OpenStack SDK:

https://review.openstack.org/#/c/200822/

We will not use the thin interface any more.

Change-Id: Iab6648d45e855af55d1237c13e721df6d847c206

senlinclient/v1/client.py

@@ -13,7 +13,6 @@
 import inspect
 import json
 from openstack.identity import identity_service
-from openstack.network.v2 import thin as thins
 from openstack import transport as trans
 
 from senlinclient.common import exc as client_exc
@@ -34,12 +33,6 @@ class Client(object):
         xport = trans.Transport(verify=opts.verify)
         return xport.get(argument).text
 
-    def thin(self):
-        # Authenticate should be done before this.
-        request = thins.Thin()
-        for obj in request.list_networks(self.session):
-            print(obj['id'])
-
     def session(self, cls_name):
         if cls_name is None:
             raise Exception("A cls name argument must be specified")