test: name Mixin with MixinPrefix

pylint understands this and does not report errors about accessing
undefined members.

http://pylint.pycqa.org/en/stable/faq.html#how-do-i-avoid-access-to-undefined-member-messages-in-my-mixin-classes

kedifa/test.py

@@ -96,7 +96,7 @@ class KedifaMixin(object):
 
 
 _clean_caucased_snapshot = None
-class KedifaMixinCaucase(KedifaMixin):
+class KedifaCaucaseMixin(KedifaMixin):
   def _startCaucaseServer(self, argv=(), timeout=10):
     """
     Start caucased server
@@ -370,7 +370,7 @@ ez+ONyvetfvjD8cxyQ==
     return reserved_reference
 
   def setUp(self):
-    super(KedifaMixinCaucase, self).setUp()
+    super(KedifaCaucaseMixin, self).setUp()
     self.createPem()
 
     self.setUpCaucase()
@@ -388,7 +388,7 @@ ez+ONyvetfvjD8cxyQ==
 
 
 @unittest.skipIf(sys.version_info >= (3, ), 'kedifa currently supports python 2 only')
-class KedifaIntegrationTest(KedifaMixinCaucase, unittest.TestCase):
+class KedifaIntegrationTest(KedifaCaucaseMixin, unittest.TestCase):
   def assertAnyLogEntry(self, entry):
     with open(self.logfile) as fh:
       log_line_list = fh.readlines()