fix bug in encrypted channel where replace doesn't exist on maps

Author: daniellevass

src/main/java/com/pusher/client/channel/impl/PrivateEncryptedChannelImpl.java

@@ -185,7 +185,7 @@ private PusherEvent decryptMessage(String message) {
                 encryptedReceivedData.getCiphertext(),
                 encryptedReceivedData.getNonce());
 
-        receivedMessage.replace("data", decryptedData);
+        receivedMessage.put("data", decryptedData);
 
         return new PusherEvent(receivedMessage);
     }