Collators get incoming parachain messages (#149)

* refactor out a consensus data fetcher from table router

* move statement checking logic into router

* refuse to start authority if collator

* support building the table router asynchronously

* instantiate_consensus does not overwrite old

* update key in new consensus if there was none before

* collator collects ingress from network

* test produced egress roots

* fix adder-collator compilation

* address first grumbles

* integrate new gossip with collator network launch

* address review

polkadot/validation/src/attestation_service.rs

@@ -118,6 +118,7 @@ pub(crate) fn start<C, N, P>(
 		N: Network + Send + Sync + 'static,
 		N::TableRouter: Send + 'static,
 		<<N::TableRouter as TableRouter>::FetchIncoming as IntoFuture>::Future: Send + 'static,
+		<N::BuildTableRouter as IntoFuture>::Future: Send + 'static,
 {
 	const TIMER_DELAY: Duration = Duration::from_secs(5);
 	const TIMER_INTERVAL: Duration = Duration::from_secs(30);