Update jsonrpc dependency syntax

src/lib.rs

@@ -64,6 +64,7 @@ extern crate byteorder;
 extern crate chrono;
 extern crate generic_array;
 extern crate itertools;
+extern crate jsonrpc_core;
 #[macro_use]
 extern crate jsonrpc_macros;
 extern crate jsonrpc_http_server;