Change 'Member' role reference to 'member'

'Member' role has been deprecated and replaced by 'member'.
The patch replaces the leftover occurrences of 'Member' by 'member'.

Change-Id: I857655b8568eb2df1bb9bc263117119388d42f01
Closes-Bug: #1330132
diff --git a/tempest/tests/lib/common/test_dynamic_creds.py b/tempest/tests/lib/common/test_dynamic_creds.py
index 4723458..1aec1dc 100644
--- a/tempest/tests/lib/common/test_dynamic_creds.py
+++ b/tempest/tests/lib/common/test_dynamic_creds.py
@@ -110,7 +110,7 @@
                           (200,
                            {'roles': [{'id': id, 'name': name},
                                       {'id': '1', 'name': 'FakeRole'},
-                                      {'id': '2', 'name': 'Member'}]}))))
+                                      {'id': '2', 'name': 'member'}]}))))
         return roles_fix
 
     def _mock_list_2_roles(self):
@@ -139,7 +139,7 @@
             return_value=(rest_client.ResponseBody
                           (200, {'roles': [
                               {'id': '1', 'name': 'FakeRole'},
-                              {'id': '2', 'name': 'Member'}]}))))
+                              {'id': '2', 'name': 'member'}]}))))
         return roles_fix
 
     def _mock_list_ec2_credentials(self, user_id, tenant_id):
@@ -664,6 +664,6 @@
         with mock.patch('tempest.lib.common.dynamic_creds.LOG') as log_mock:
             creds._create_creds()
             log_mock.warning.assert_called_once_with(
-                "Member role already exists, ignoring conflict.")
+                "member role already exists, ignoring conflict.")
         creds.creds_client.assign_user_role.assert_called_once_with(
-            mock.ANY, mock.ANY, 'Member')
+            mock.ANY, mock.ANY, 'member')