Merge pull request #9 from samstokes/patch-1

Fix Config.addSerialization() parameter type
diff --git a/src/jvm/backtype/storm/Config.java b/src/jvm/backtype/storm/Config.java
index d68de39..e5008e9 100644
--- a/src/jvm/backtype/storm/Config.java
+++ b/src/jvm/backtype/storm/Config.java
@@ -343,7 +343,7 @@
         put(Config.TOPOLOGY_MESSAGE_TIMEOUT_SECS, secs);
     }
     
-    public void addSerialization(int token, Class<ISerialization> serialization) {
+    public void addSerialization(int token, Class<? extends ISerialization> serialization) {
         if(!containsKey(Config.TOPOLOGY_SERIALIZATIONS)) {
             put(Config.TOPOLOGY_SERIALIZATIONS, new HashMap());
         }