* 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
Wei Tang