Merge pull request #899 from Axelrod-Python/filter-tests

Add missing tests for filters.py

Author: drvinceknight

axelrod/strategies/_filters.py

@@ -44,10 +44,6 @@ class ExampleStrategy(Player):
         the value and operator passed to the function.
     """
     classifier_value = player.classifier[classifier_key]
-    if (isinstance(classifier_value, str) and
-            classifier_value.lower() == 'infinity'):
-        classifier_value = float('inf')
-
     return operator(classifier_value, value)