Remove blocking sync -> import-queue operations (#1818)

* remove blocking sync -> import-queue operations

add specialization to testnet

remove add peer default impl on TestNetFactory

* remove empty brackets from dummy specialization

* nits

* make mut_peers take an fn once

* add SpecializationFactory trait in test

* remove add_peer imple in grandpa, fix typo

* use cmp::max for best importing number comparison

* remove import of non-existent create_peer

* add sender to start message

substrate/core/consensus/aura/src/lib.rs

@@ -699,11 +699,12 @@ mod tests {
 	const TEST_ROUTING_INTERVAL: Duration = Duration::from_millis(50);
 
 	pub struct AuraTestNet {
-		peers: Vec<Arc<Peer<()>>>,
+		peers: Vec<Arc<Peer<(), DummySpecialization>>>,
 		started: bool,
 	}
 
 	impl TestNetFactory for AuraTestNet {
+		type Specialization = DummySpecialization;
 		type Verifier = AuraVerifier<PeersClient, NothingExtra>;
 		type PeerData = ();
 
@@ -734,15 +735,15 @@ mod tests {
 			})
 		}
 
-		fn peer(&self, i: usize) -> &Peer<Self::PeerData> {
+		fn peer(&self, i: usize) -> &Peer<Self::PeerData, DummySpecialization> {
 			&self.peers[i]
 		}
 
-		fn peers(&self) -> &Vec<Arc<Peer<Self::PeerData>>> {
+		fn peers(&self) -> &Vec<Arc<Peer<Self::PeerData, DummySpecialization>>> {
 			&self.peers
 		}
 
-		fn mut_peers<F: Fn(&mut Vec<Arc<Peer<Self::PeerData>>>)>(&mut self, closure: F) {
+		fn mut_peers<F: FnOnce(&mut Vec<Arc<Peer<Self::PeerData, DummySpecialization>>>)>(&mut self, closure: F) {
 			closure(&mut self.peers);
 		}