Change import of exceptions for keystoneclient

Keystoneclients uses module `keystoneclient.exceptions` for storing
exceptions, so it needed to import `keystoneclient.exceptions`
instead of `keystoneclient.apiclient.exceptions` in tempest.

Change-Id: I68cb50bd092e9cc304710bf7748a1c0de5554612
Closes-Bug: #1276093
diff --git a/tempest/scenario/manager.py b/tempest/scenario/manager.py
index 59a3aeb..705d5c1 100644
--- a/tempest/scenario/manager.py
+++ b/tempest/scenario/manager.py
@@ -22,7 +22,7 @@
 import cinderclient.client
 import glanceclient
 import heatclient.client
-import keystoneclient.apiclient.exceptions
+import keystoneclient.exceptions
 import keystoneclient.v2_0.client
 import netaddr
 from neutronclient.common import exceptions as exc
@@ -146,7 +146,7 @@
             keystone_admin.roles.add_user_role(self.identity_client.user_id,
                                                member_role.id,
                                                self.identity_client.tenant_id)
-        except keystoneclient.apiclient.exceptions.Conflict:
+        except keystoneclient.exceptions.Conflict:
             pass
 
         return swiftclient.Connection(auth_url, username, password,