Remove unused PoA<>Substrate bridge (#1210)

* Decouple the PoA bridge code from Rialto
* Remove Rialto PoA bridge code
* Remove relays/bin-ethereum code
* Remove relays/client-ethereum code
* Remove modules/ethereum code
* Remove modules/ethereum-contract-builtin code
* Remove PoA bridge documentation
* Remove primitives/ethereum-poa code
* Decouple Rialto from currency-exchange
* Fix building with runtime-benchmarks
* Fix should_encode_bridge_send_message_call test
    Because we removed some runtime modules/pallets, the
    substrate2substrate bridge pallet has a different index within
    the runtime so its calls have a different encoding.
    Update the test to use the new encoding.
* Update readme - no more PoA bridge
* Remove deployments/bridges/poa-rialto
    Also removes:
    - deployments/networks/eth-poa.yml
    - deployments/networks/OpenEthereum.Dockerfile
* Remove deployments/dev/poa-config
* Update deployments readme - no more PoA bridge
* Remove eth-related scripts
    Deletes:
    - deployments/networks/eth-poa.yml
    - scripts/run-openethereum-node.sh
* Remove poa-relay from gitlab-ci
* Dockerfiles to use substrate-relay as default
* Remove modules/currency-exchange code
* Remove primitives/currency-exchange code

Signed-off-by: acatangiu <adrian@parity.io>

bridges/bin/rialto/node/src/chain_spec.rs

@@ -17,9 +17,9 @@
 use bp_rialto::derive_account_from_millau_id;
 use polkadot_primitives::v1::{AssignmentId, ValidatorId};
 use rialto_runtime::{
-	AccountId, BabeConfig, BalancesConfig, BridgeKovanConfig, BridgeMillauMessagesConfig,
-	BridgeRialtoPoaConfig, ConfigurationConfig, GenesisConfig, GrandpaConfig, SessionConfig,
-	SessionKeys, Signature, SudoConfig, SystemConfig, WASM_BINARY,
+	AccountId, BabeConfig, BalancesConfig, BridgeMillauMessagesConfig, ConfigurationConfig,
+	GenesisConfig, GrandpaConfig, SessionConfig, SessionKeys, Signature, SudoConfig, SystemConfig,
+	WASM_BINARY,
 };
 use serde_json::json;
 use sp_authority_discovery::AuthorityId as AuthorityDiscoveryId;
@@ -216,8 +216,6 @@ fn testnet_genesis(
 			authorities: Vec::new(),
 			epoch_config: Some(rialto_runtime::BABE_GENESIS_EPOCH_CONFIG),
 		},
-		bridge_rialto_poa: load_rialto_poa_bridge_config(),
-		bridge_kovan: load_kovan_bridge_config(),
 		grandpa: GrandpaConfig { authorities: Vec::new() },
 		sudo: SudoConfig { key: root_key },
 		session: SessionConfig {
@@ -291,22 +289,6 @@ fn testnet_genesis(
 	}
 }
 
-fn load_rialto_poa_bridge_config() -> BridgeRialtoPoaConfig {
-	BridgeRialtoPoaConfig {
-		initial_header: rialto_runtime::rialto_poa::genesis_header(),
-		initial_difficulty: 0.into(),
-		initial_validators: rialto_runtime::rialto_poa::genesis_validators(),
-	}
-}
-
-fn load_kovan_bridge_config() -> BridgeKovanConfig {
-	BridgeKovanConfig {
-		initial_header: rialto_runtime::kovan::genesis_header(),
-		initial_difficulty: 0.into(),
-		initial_validators: rialto_runtime::kovan::genesis_validators(),
-	}
-}
-
 #[test]
 fn derived_dave_account_is_as_expected() {
 	let dave = get_account_id_from_seed::<sr25519::Public>("Dave");