Delete Savanna element in client list

There are not savanna any more.
The Savannaclient are also deprecated, so just delete it!

Change-Id: I3df64eb6ca1f6b6b663b6fe41f678ebc60ffd896
diff --git a/tempest/hacking/checks.py b/tempest/hacking/checks.py
index e2d6585..4123ae5 100644
--- a/tempest/hacking/checks.py
+++ b/tempest/hacking/checks.py
@@ -19,7 +19,7 @@
 
 
 PYTHON_CLIENTS = ['cinder', 'glance', 'keystone', 'nova', 'swift', 'neutron',
-                  'ironic', 'savanna', 'heat', 'sahara']
+                  'ironic', 'heat', 'sahara']
 
 PYTHON_CLIENT_RE = re.compile('import (%s)client' % '|'.join(PYTHON_CLIENTS))
 TEST_DEFINITION = re.compile(r'^\s*def test.*')