Make AuthorityId generic (#1296)

* BlockAuthorityId convenience type

* Rename AuthorityId -> Ed25519AuthorityId to make it more precise

* Generalize AuthorityId up to substrate-client

* Fix in client-db

* rename: BlockAuthorityId -> AuthorityIdFor

* typo: should be digest item

* Fix test-runtime authorityId mismatch

One states that AuthorityId is u64 while the other states that it's Ed25519AuthorityId.

* Fix more u64 - Ed25519AuthorityId mismatch

* Fix compile of most of the srml modules

* Continue to pin aura and grandpa with ed25519 and fix compile

* Add MaybeHash trait

* Fix node-runtime compile

* Fix network tests

substrate/core/client/src/runtime_api.rs

@@ -21,7 +21,7 @@
 pub use state_machine::OverlayedChanges;
 #[doc(hidden)]
 pub use runtime_primitives::{
-	traits::{Block as BlockT, GetNodeBlockType, GetRuntimeBlockType, ApiRef, RuntimeApiInfo},
+	traits::{AuthorityIdFor, Block as BlockT, GetNodeBlockType, GetRuntimeBlockType, ApiRef, RuntimeApiInfo},
 	generic::BlockId, transaction_validity::TransactionValidity
 };
 #[doc(hidden)]
@@ -34,7 +34,7 @@ pub use codec::{Encode, Decode};
 #[cfg(feature = "std")]
 use error;
 use rstd::vec::Vec;
-use primitives::{AuthorityId, OpaqueMetadata};
+use primitives::OpaqueMetadata;
 
 
 /// Something that can be constructed to a runtime api.
@@ -91,7 +91,7 @@ decl_runtime_apis! {
 		/// Returns the version of the runtime.
 		fn version() -> RuntimeVersion;
 		/// Returns the authorities.
-		fn authorities() -> Vec<AuthorityId>;
+		fn authorities() -> Vec<AuthorityIdFor<Block>>;
 		/// Execute the given block.
 		fn execute_block(block: Block);
 		/// Initialise a block with the given header.