Do not include :code in the storage proof if not required (#480)

This is basically a hack that prevents the inclusion of `:code` in the
storage proof. A proper fix requires some changes to the trie crate to
not include nodes that aren't read.

test/runtime/src/lib.rs

@@ -269,11 +269,11 @@ construct_runtime! {
 		UncheckedExtrinsic = UncheckedExtrinsic,
 	{
 		System: frame_system::{Pallet, Call, Storage, Config, Event<T>},
+		ParachainSystem: cumulus_pallet_parachain_system::{Pallet, Call, Storage, Inherent, Event<T>, Config},
 		Timestamp: pallet_timestamp::{Pallet, Call, Storage, Inherent},
 		Balances: pallet_balances::{Pallet, Call, Storage, Config<T>, Event<T>},
 		Sudo: pallet_sudo::{Pallet, Call, Storage, Config<T>, Event<T>},
 		RandomnessCollectiveFlip: pallet_randomness_collective_flip::{Pallet, Call, Storage},
-		ParachainSystem: cumulus_pallet_parachain_system::{Pallet, Call, Storage, Inherent, Event<T>},
 		TransactionPayment: pallet_transaction_payment::{Pallet, Storage},
 	}
 }