Revert "Add condition for is_alternator to return false for junk hist…

…ory"

This reverts commit abd4ffa.

axelrod/strategies/hunter.py

@@ -49,7 +49,7 @@ def strategy(self, opponent: Player) -> Action:
 
 def is_alternator(history: List[Action]) -> bool:
     for i in range(len(history) - 1):
-        if history[i] == history[i + 1] or history[i] not in (C, D):
+        if history[i] == history[i + 1]:
             return False
     return True