Migrate rpc-servers, serializer, service and sr-io to the 2018 edition (#1732)

substrate/core/serializer/Cargo.toml

@@ -2,6 +2,7 @@
 name = "substrate-serializer"
 version = "0.1.0"
 authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
 
 [dependencies]
 serde = { version = "1.0", default-features = false }

substrate/core/serializer/src/lib.rs

@@ -21,9 +21,6 @@
 
 #![warn(missing_docs)]
 
-extern crate serde;
-extern crate serde_json;
-
 pub use serde_json::{from_str, from_slice, from_reader, Result, Error};
 
 const PROOF: &str = "Serializers are infallible; qed";