Make runtime api generate version and identifier information (#1226)

* Make `decl_runtime_apis!` implement `RuntimeApiInfo` for all runtime
apis

* Make the runtime side generate the info constants as well

* Make `RuntimeApiInfo` implementation use the correct generics

* Adds a test for the runtime api info stuff

* Remove duplicated code by using block from `test-client`

* Adds `compile_fail` tests for `api_version`

* Adds documentation for `api_version`

* Make `impl_runtime_apis!` generate `RUNTIME_API_VERSIONS`

* Update documentation and tests for `RUNTIME_API_VERSIONS`

* Implement `has_api` by using the `RuntimeApiInfo`

* Make `impl_runtime_apis` check that trait identifiers are unique

* Prefix all runtime api function with the corresponding trait

So `execute_block` will be called `Core_execute_block`.
This makes it possible to have traits implement a function with the
same name.

* Rebase master

* Update after master rebase

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

@@ -17,7 +17,7 @@
 use super::*;
 use jsonrpc_macros::pubsub;
 use test_client::{self, TestClient};
-use test_client::runtime::{Block, Header};
+use test_client::runtime::{Block, Header, VERSION};
 use consensus::BlockOrigin;
 
 #[test]
@@ -259,13 +259,6 @@ fn should_return_runtime_version() {
 
 	assert_matches!(
 		client.runtime_version(None.into()),
-		Ok(ref ver) if ver == &RuntimeVersion {
-			spec_name: "test".into(),
-			impl_name: "parity-test".into(),
-			authoring_version: 1,
-			spec_version: 1,
-			impl_version: 1,
-			apis: (&[][..]).into()
-		}
+		Ok(ref ver) if ver == &VERSION
 	);
 }