Remove unneeded Serde requirements (#1076)

* Remove superfluous serde requirements.

* Try to ensure hash is serde

* Fixups

* Building again

* Attempt to reenable Block (doesn't build)

* Fixes compilation for node cli

* Fixes test compilation

* Fix wasm

* Fix tests

* Remove unneeded changes

* Fix up comments

* Reenable some code

* Compile error when origin misused.

* Remove unnecessary includes of `serde_derive`

* Cleanups

substrate/srml/session/Cargo.toml

@@ -6,7 +6,6 @@ authors = ["Parity Technologies <admin@parity.io>"]
 [dependencies]
 hex-literal = "0.1.0"
 serde = { version = "1.0", default-features = false }
-serde_derive = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false}
 substrate-primitives = { path = "../../core/primitives", default-features = false }
 parity-codec = { version = "2.1", default-features = false }
@@ -23,7 +22,6 @@ srml-timestamp = { path = "../timestamp", default-features = false }
 default = ["std"]
 std = [
 	"serde/std",
-	"serde_derive",
 	"safe-mix/std",
 	"parity-codec/std",
 	"parity-codec-derive/std",

substrate/srml/session/src/lib.rs

@@ -19,10 +19,6 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-#[cfg(feature = "std")]
-#[macro_use]
-extern crate serde_derive;
-
 extern crate sr_std as rstd;
 
 #[macro_use]