Transaction Fee Module (#1648)

* wip

* Split bytes fee charging and charging by amount into different traits.

* Move to edition 2018.

* Implemented charge fee traits for fees module.

* Implemented 'on_finalise' for fee module.

* Updated fees finalize impl.

* Renaming and documentation update.

* Added overflow & underflow check for fee calculation.

* Added mock and unit tests for fee module.

* More unit tests for fees module.

* Fixed srml-executive unit tests.

* Remove transaction base/bytes fee from balances module, fix unit tests.

* fix compile error

* Fixed unit test.

* Minor fixes.

* Bump spec version.

* Bump spec version.

* Updated fees module and runtime wasm.

* Fees module code style improvement; updated runtime wasm.

* Bump spec and impl version.

substrate/node-template/src/chain_spec.rs

@@ -1,7 +1,7 @@
 use primitives::{Ed25519AuthorityId, ed25519};
 use node_template_runtime::{
 	AccountId, GenesisConfig, ConsensusConfig, TimestampConfig, BalancesConfig,
-	SudoConfig, IndicesConfig
+	SudoConfig, IndicesConfig, FeesConfig,
 };
 use substrate_service;
 
@@ -90,8 +90,6 @@ fn testnet_genesis(initial_authorities: Vec<Ed25519AuthorityId>, endowed_account
 			ids: endowed_accounts.clone(),
 		}),
 		balances: Some(BalancesConfig {
-			transaction_base_fee: 1,
-			transaction_byte_fee: 0,
 			existential_deposit: 500,
 			transfer_fee: 0,
 			creation_fee: 0,
@@ -101,5 +99,9 @@ fn testnet_genesis(initial_authorities: Vec<Ed25519AuthorityId>, endowed_account
 		sudo: Some(SudoConfig {
 			key: root_key,
 		}),
+		fees: Some(FeesConfig {
+			transaction_base_fee: 1,
+			transaction_byte_fee: 0,
+		})
 	}
 }