Migrate to the 2018 edition (#273)

polkadot/statement-table/src/generic.rs

@@ -28,6 +28,8 @@ use std::collections::hash_map::{HashMap, Entry};
 use std::hash::Hash;
 use std::fmt::Debug;
 
+use parity_codec::{Encode, Decode};
+
 /// Context for the statement table.
 pub trait Context {
 	/// A authority ID

polkadot/statement-table/src/lib.rs

@@ -14,13 +14,6 @@
 //! propose and attest to validity of candidates, and those who can only attest
 //! to availability.
 
-extern crate parity_codec as codec;
-extern crate substrate_primitives;
-extern crate polkadot_primitives as primitives;
-
-#[macro_use]
-extern crate parity_codec_derive;
-
 pub mod generic;
 
 pub use generic::Table;