substrate: peer_store: log warn on disconnecting because of reputation (

paritytech#1299)

* substrate: peer_store: log error on disconnecting because of reputation

Disconnecting and banning a peer because of negative reputation is
usually an indicative of one of two things:
1. We've got a bug that forces disconnects.
2. We've got malicious peers that try to attack us.

We both cases I don't think we should hide this behind a trace log
and we should log errors, so that things are easy to notice and
debug/mitigated.

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

* Move from error to warn

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

---------

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

substrate/client/network/src/peer_store.rs

@@ -222,7 +222,7 @@ impl PeerStoreInner {
 		if peer_info.reputation < BANNED_THRESHOLD {
 			self.protocols.iter().for_each(|handle| handle.disconnect_peer(peer_id));
 
-			log::trace!(
+			log::warn!(
 				target: LOG_TARGET,
 				"Report {}: {:+} to {}. Reason: {}. Banned, disconnecting.",
 				peer_id,