Rust 2018 cleanup

drone/src/drone.rs

@@ -7,6 +7,8 @@
 use bincode::{deserialize, serialize};
 use byteorder::{ByteOrder, LittleEndian};
 use bytes::Bytes;
+use log::*;
+use serde_derive::{Deserialize, Serialize};
 use solana_metrics;
 use solana_metrics::influxdb;
 use solana_sdk::hash::Hash;