Simplify filter in list comprehension

Author: meatballs

axelrod/tests/integration/test_names.py

@@ -5,7 +5,7 @@
 class TestNames(unittest.TestCase):
 
     def test_all_strategies_have_names(self):
-        names = [s.name for s in all_strategies if s.name is not None]
+        names = [s.name for s in all_strategies if s.name]
         self.assertEqual(len(names), len(all_strategies))
 
     def test_all_names_are_unique(self):