Use substrate codec for network messages (#333)

* Use substrate codec for network messages

* Version bump

* Removed redundant format

polkadot/network/src/collator_pool.rs

@@ -18,6 +18,7 @@
 
 use polkadot_primitives::{AccountId, Hash};
 use polkadot_primitives::parachain::{Id as ParaId, Collation};
+use codec;
 
 use futures::sync::oneshot;
 
@@ -27,12 +28,28 @@ use std::time::{Duration, Instant};
 const COLLATION_LIFETIME: Duration = Duration::from_secs(60 * 5);
 
 /// The role of the collator. Whether they're the primary or backup for this parachain.
-#[derive(PartialEq, Debug, Serialize, Deserialize)]
+#[derive(PartialEq, Debug, Clone, Copy)]
 pub enum Role {
 	/// Primary collators should send collations whenever it's time.
-	Primary,
+	Primary = 0,
 	/// Backup collators should not.
-	Backup,
+	Backup = 1,
+}
+
+impl codec::Encode for Role {
+	fn encode_to<T: codec::Output>(&self, dest: &mut T) {
+		dest.push_byte(*self as u8);
+	}
+}
+
+impl codec::Decode for Role {
+	fn decode<I: codec::Input>(input: &mut I) -> Option<Self> {
+		match input.read_byte()? {
+			x if x == Role::Primary as u8 => Some(Role::Primary),
+			x if x == Role::Backup as u8 => Some(Role::Backup),
+			_ => None,
+		}
+	}
 }
 
 /// A maintenance action for the collator set.