Distinguish between excess server load and excessive connection work.

src/cpp/ripple/RPCErr.cpp

@@ -72,6 +72,7 @@ Json::Value rpcError(int iError, Json::Value jvResult)
 		{ rpcUNKNOWN_COMMAND,		"unknownCmd",		"Unknown method."										},
 		{ rpcWRONG_SEED,			"wrongSeed",		"The regular key does not point as the master key."		},
 		{ rpcTOO_BUSY,				"tooBusy",			"The server is too busy to help you now."               },
+		{ rpcSLOW_DOWN,				"slowDown",			"You are placing too much load on the server."			},
 	};
 
 	int		i;

src/cpp/ripple/RPCErr.h

@@ -18,6 +18,7 @@ enum {
 	rpcNO_EVENTS,
 	rpcNOT_STANDALONE,
 	rpcTOO_BUSY,
+	rpcSLOW_DOWN,
 
 	// Networking
 	rpcNO_CLOSED,

src/cpp/ripple/WSConnection.h

@@ -93,7 +93,7 @@ public:
 			connection_ptr ptr = mConnection.lock();
 			if (ptr)
 				ptr->close(websocketpp::close::status::PROTOCOL_ERROR, "overload");
-			return rpcError(rpcTOO_BUSY);
+			return rpcError(rpcSLOW_DOWN);
 		}
 
 		if (!jvRequest.isMember("command"))