Make add_router_to_l3_agent use **kwargs

As we discussed on
http://lists.openstack.org/pipermail/openstack-dev/2015-July/068864.html
All http POST/PUT methods need to contain **kwargs as their arguments.

This patch makes add_router_to_l3_agent of network client
to use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I2f17062076a3a356bbb2f67099bcc9b3edd2f76f
diff --git a/tempest/api/network/admin/test_l3_agent_scheduler.py b/tempest/api/network/admin/test_l3_agent_scheduler.py
index d5556b8..36747a3 100644
--- a/tempest/api/network/admin/test_l3_agent_scheduler.py
+++ b/tempest/api/network/admin/test_l3_agent_scheduler.py
@@ -97,7 +97,7 @@
         l3_agent_ids = list()
         self.admin_client.add_router_to_l3_agent(
             self.agent['id'],
-            self.router['id'])
+            router_id=self.router['id'])
         body = (
             self.admin_client.list_l3_agents_hosting_router(self.router['id']))
         for agent in body['agents']:
diff --git a/tempest/scenario/test_network_basic_ops.py b/tempest/scenario/test_network_basic_ops.py
index 28f1cd3..2f0b406 100644
--- a/tempest/scenario/test_network_basic_ops.py
+++ b/tempest/scenario/test_network_basic_ops.py
@@ -726,7 +726,7 @@
         target_agent = list(hosting_agents if no_migration else
                             agent_list - hosting_agents)[0]
         schedule_router(target_agent,
-                        self.router['id'])
+                        router_id=self.router['id'])
         self.assertEqual(
             target_agent,
             list_hosts(self.router.id)['agents'][0]['id'],
diff --git a/tempest/services/network/json/network_client.py b/tempest/services/network/json/network_client.py
index 5a4229c..2c6829c 100644
--- a/tempest/services/network/json/network_client.py
+++ b/tempest/services/network/json/network_client.py
@@ -317,10 +317,12 @@
         uri = '/routers/%s/l3-agents' % router_id
         return self.list_resources(uri)
 
-    def add_router_to_l3_agent(self, agent_id, router_id):
+    def add_router_to_l3_agent(self, agent_id, **kwargs):
+        # TODO(piyush): Current api-site doesn't contain this API description.
+        # After fixing the api-site, we need to fix here also for putting the
+        # link to api-site.
         uri = '/agents/%s/l3-routers' % agent_id
-        post_body = {"router_id": router_id}
-        return self.create_resource(uri, post_body)
+        return self.create_resource(uri, kwargs)
 
     def remove_router_from_l3_agent(self, agent_id, router_id):
         uri = '/agents/%s/l3-routers/%s' % (agent_id, router_id)