Fixing deprecated methods of tokio_core

ethcore/light/src/on_demand/mod.rs

@@ -18,6 +18,9 @@
 //! The request service is implemented using Futures. Higher level request handlers
 //! will take the raw data received here and extract meaningful results from it.
 
+// TODO [ToDr] Suppressing deprecation warnings. Rob will fix the API anyway.
+#![allow(deprecated)]
+
 use std::collections::HashMap;
 use std::sync::Arc;