Return complete response from instance usage client

Currently compute instance_usage_audit_log_client returns Response by
removing top key from Response.
For example-
 return service_client.ResponseBody(resp, body['instance_usage_audit_log'])

As service clients are in direction to move to Tempest-lib, all
service clients should return Response without any truncation.
One good example is Resource pagination links which are lost with current
way of return value. Resource pagination links are present in parallel
(not inside) to top key of Response.

This patch makes compute instance_usage_audit_log_client to return complete
Response body.

Change-Id: I11038a3b5e263918c150bbb304ae40a905329bef
Implements: blueprint method-return-value-and-move-service-clients-to-lib
diff --git a/tempest/api/compute/admin/test_instance_usage_audit_log.py b/tempest/api/compute/admin/test_instance_usage_audit_log.py
index 189c316..6976783 100644
--- a/tempest/api/compute/admin/test_instance_usage_audit_log.py
+++ b/tempest/api/compute/admin/test_instance_usage_audit_log.py
@@ -31,7 +31,8 @@
     @test.idempotent_id('25319919-33d9-424f-9f99-2c203ee48b9d')
     def test_list_instance_usage_audit_logs(self):
         # list instance usage audit logs
-        body = self.adm_client.list_instance_usage_audit_logs()
+        body = (self.adm_client.list_instance_usage_audit_logs()
+                ["instance_usage_audit_logs"])
         expected_items = ['total_errors', 'total_instances', 'log',
                           'num_hosts_running', 'num_hosts_done',
                           'num_hosts', 'hosts_not_run', 'overall_status',
@@ -44,8 +45,9 @@
     def test_get_instance_usage_audit_log(self):
         # Get instance usage audit log before specified time
         now = datetime.datetime.now()
-        body = self.adm_client.show_instance_usage_audit_log(
+        body = (self.adm_client.show_instance_usage_audit_log(
             urllib.quote(now.strftime("%Y-%m-%d %H:%M:%S")))
+            ["instance_usage_audit_log"])
 
         expected_items = ['total_errors', 'total_instances', 'log',
                           'num_hosts_running', 'num_hosts_done', 'num_hosts',
diff --git a/tempest/services/compute/json/instance_usage_audit_log_client.py b/tempest/services/compute/json/instance_usage_audit_log_client.py
index f06a675..4d9625e 100644
--- a/tempest/services/compute/json/instance_usage_audit_log_client.py
+++ b/tempest/services/compute/json/instance_usage_audit_log_client.py
@@ -28,13 +28,11 @@
         body = json.loads(body)
         self.validate_response(schema.list_instance_usage_audit_log,
                                resp, body)
-        return service_client.ResponseBody(resp,
-                                           body["instance_usage_audit_logs"])
+        return service_client.ResponseBody(resp, body)
 
     def show_instance_usage_audit_log(self, time_before):
         url = 'os-instance_usage_audit_log/%s' % time_before
         resp, body = self.get(url)
         body = json.loads(body)
         self.validate_response(schema.get_instance_usage_audit_log, resp, body)
-        return service_client.ResponseBody(resp,
-                                           body["instance_usage_audit_log"])
+        return service_client.ResponseBody(resp, body)