Generalised Transaction Queue API (#741)

* First effort

* API versioning

* Introduce validate_transaction

* Introduce the API plus fixes.

* Docs

* Typo

* Add longevity parameter to transaction validity info.

substrate/core/rpc/Cargo.toml

@@ -10,7 +10,7 @@ jsonrpc-macros = { git="https://github.com/paritytech/jsonrpc.git" }
 jsonrpc-pubsub = { git="https://github.com/paritytech/jsonrpc.git" }
 log = "0.3"
 parking_lot = "0.4"
-parity-codec = { version = "~1.0" }
+parity-codec = { version = "1.1" }
 substrate-client = { path = "../client" }
 substrate-executor = { path = "../executor" }
 substrate-extrinsic-pool = { path = "../extrinsic-pool" }

substrate/core/rpc/src/chain/tests.rs

@@ -202,6 +202,7 @@ fn should_return_runtime_version() {
 			authoring_version: 1,
 			spec_version: 1,
 			impl_version: 1,
+			apis: (&[][..]).into()
 		}
 	);
 }