Add the strategy to strategies pool

Author: margaret

axelrod/strategies/_strategies.py

@@ -46,7 +46,7 @@
 from .mindreader import MindReader, ProtectedMindReader, MirrorMindReader
 from .mutual import Desperate, Hopeless, Willing
 from .oncebitten import OnceBitten, FoolMeOnce, ForgetfulFoolMeOnce, FoolMeForever
-from .prober import (Prober, Prober2, Prober3, HardProber,
+from .prober import (Prober, Prober2, Prober3, Prober4, HardProber,
                      NaiveProber, RemorsefulProber)
 from .punisher import Punisher, InversePunisher
 from .qlearner import RiskyQLearner, ArrogantQLearner, HesitantQLearner, CautiousQLearner
@@ -164,6 +164,7 @@
     Prober,
     Prober2,
     Prober3,
+    Prober4,
     ProtectedMindReader,
     Punisher,
     Raider,