Consensus Engines Implementation: Aura (#911)

* Generalize BlockImport

 - move ImportBlock, BlockOrigin, ImportResult into shared sr-primitives
 - let Consensus provide  and  traits again
 - update consensus traits to latest development
 - implement traits on client::Client, test_client::TestClient
 - update RHD to use the new import_block API

* Move ImportBlock into consensus-common
* Send import notification in aura tests
* Integrating aura into service
* Make Signatures more generic
* Aura Block Production with the given key
* run aura on the thread pool
* start at exact step start in aura
* Add needed wasm blob, in leiu of better solutions.
* Make API ids consistent with traits and bring upstream for sharing.
* Add decrease_free_balance to Balances module
* Encode `Metadata` once instead of two times
* Bitops include xor
* Upgrade key module.
* Default pages to somewhat bigger.
* Introduce upgrade key into node
* Add `Created` event

substrate/Cargo.toml

@@ -23,6 +23,7 @@ members = [
 	"core/client",
 	"core/client/db",
 	"core/consensus/common",
+	"core/consensus/aura",
 	"core/consensus/rhd",
 	"core/executor",
 	"core/finality-grandpa",
@@ -54,6 +55,7 @@ members = [
 	"srml/system",
 	"srml/timestamp",
 	"srml/treasury",
+	"srml/upgrade-key",
 	"core/serializer",
 	"core/service",
 	"core/service/test",
@@ -64,9 +66,7 @@ members = [
 	"core/trie",
 	"core/keystore",
 	"node/cli",
-	"node/consensus",
 	"node/executor",
-	"node/network",
 	"node/primitives",
 	"node/runtime",
 	"subkey",