Fix tracking validator set in ImOnline (#3596)

* Use session::validators instead of staking::current_elected

* Basic test framework.

* Initialize validators, attempt to heartbeat.

* Use dummy crypto for im-online testing.

* Remove printlns.

* Finish test, make it invalid.

* Add reporting test.

* Finalize the test.

* Remove dumbness.

* Updates.

* Update AuRa

* Update srml/im-online/src/tests.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Derive Ord

* Add some more tests.

* Remove stray todo.

* Bump runtime version.

* Bump impl-trait-for-tuples.

* Enforce new version of trait-for-tuples.

substrate/srml/aura/src/lib.rs

@@ -53,8 +53,8 @@ use support::{
 	decl_storage, decl_module, Parameter, storage::StorageValue, traits::{Get, FindAuthor},
 	ConsensusEngineId,
 };
-use app_crypto::AppPublic;
 use sr_primitives::{
+	RuntimeAppPublic,
 	traits::{SaturatedConversion, Saturating, Zero, Member, IsMember}, generic::DigestItem,
 };
 use timestamp::OnTimestampSet;
@@ -142,7 +142,7 @@ impl ProvideInherentData for InherentDataProvider {
 
 pub trait Trait: timestamp::Trait {
 	/// The identifier type for an authority.
-	type AuthorityId: Member + Parameter + AppPublic + Default;
+	type AuthorityId: Member + Parameter + RuntimeAppPublic + Default;
 }
 
 decl_storage! {