Added __nonzero__ method on RpcConnection class.

sjrpc/core/rpcconnection.py

@@ -100,6 +100,9 @@ class RpcConnection(object):
     def __hash__(self):
         return self._sock.__hash__()
 
+    def __nonzero__(self):
+        return self._connected
+
     def run(self):
         '''
         Inbound message processing loop.