Report the correct error if someone tries to use the evented path_find through the RPC API.

(Maybe we'll add limited support for this later.)

src/cpp/ripple/CallRPC.cpp

@@ -736,6 +736,7 @@ Json::Value RPCParser::parseCommand(std::string strMethod, Json::Value jvParams)
 #endif
 
 		// Evented methods
+		{	"path_find",			&RPCParser::parseEvented,				-1, -1	},
 		{	"subscribe",			&RPCParser::parseEvented,				-1,	-1	},
 		{	"unsubscribe",			&RPCParser::parseEvented,				-1,	-1	},
 	};