Allow both consensus and runtime to limit block building (#1581)

* Limit block size in runtime,

* Add test for basic authorship.

* Store length of extrinsics instead of computing it.

* Don't rely on note_extrinsic

* Use hashed version of storage and write test.

* Recompile runtime.

substrate/srml/democracy/src/lib.rs

@@ -23,7 +23,6 @@ extern crate substrate_primitives;
 
 #[macro_use]
 extern crate parity_codec_derive;
-#[cfg_attr(not(feature = "std"), macro_use)]
 extern crate sr_std as rstd;
 #[macro_use]
 extern crate srml_support;