More dependency cleanup (#825)

* Removes `rlp` dependency

* Enable warnings about unused crates in the CI

* Remove all the unused crates

* Make tests working again

substrate/node/transaction-pool/Cargo.toml

@@ -6,7 +6,6 @@ authors = ["Parity Technologies <admin@parity.io>"]
 [dependencies]
 log = "0.4"
 error-chain = "0.12"
-parking_lot = "0.4"
 node-primitives = { path = "../primitives" }
 node-runtime = { path = "../runtime" }
 substrate-client = { path = "../../core/client" }

substrate/node/transaction-pool/src/lib.rs

@@ -21,7 +21,6 @@ extern crate substrate_primitives;
 extern crate sr_primitives;
 extern crate node_runtime as runtime;
 extern crate node_primitives as primitives;
-extern crate parking_lot;
 
 #[cfg(test)]
 extern crate substrate_keyring;