Punish offline validators, aura-style (#1216)

* make offline-reporting infrastructure more generic

* add a listener-trait for watching when the timestamp has been set

* prevent inclusion of empty offline reports

* add test for exclusion

* generate aura-offline reports

* ability to slash many times for being offline "multiple" times

* Logic for punishing validators for missing aura steps

* stub tests

* pave way for verification of timestamp vs slot

* alter aura import queue to wait for timestamp

* check timestamp matches seal

* do inherent check properly

* service compiles

* all tests compile

* test srml-aura logic

* aura tests pass

* everything builds

* some more final tweaks to block authorship for aura

* switch to manual delays before step

* restore substrate-consensus-aura to always std and address grumbles

* update some state roots in executor tests

* node-executor tests pass

* get most tests passing

* address grumbles

substrate/core/test-runtime/src/lib.rs

@@ -24,6 +24,7 @@ extern crate serde;
 extern crate sr_std as rstd;
 extern crate parity_codec as codec;
 extern crate sr_primitives as runtime_primitives;
+extern crate substrate_consensus_aura_primitives as consensus_aura;
 
 #[macro_use]
 extern crate substrate_client as client;
@@ -64,6 +65,7 @@ use primitives::AuthorityId;
 use primitives::OpaqueMetadata;
 #[cfg(any(feature = "std", test))]
 use runtime_version::NativeVersion;
+use consensus_aura::api as aura_api;
 
 /// Test runtime version.
 pub const VERSION: RuntimeVersion = RuntimeVersion {
@@ -234,7 +236,7 @@ impl_runtime_apis! {
 		}
 
 		fn check_inherents(_block: Block, _data: ()) -> Result<(), CheckInherentError> {
-			unimplemented!()
+			Ok(())
 		}
 
 		fn random_seed() -> <Block as BlockT>::Hash {
@@ -247,4 +249,8 @@ impl_runtime_apis! {
 			system::balance_of(id)
 		}
 	}
+
+	impl aura_api::AuraApi<Block> for Runtime {
+		fn slot_duration() -> u64 { 1 }
+	}
 }