set CHAIN_ID for Classic (#3934)

* configurable CHAIN_ID

* set CHAIN_ID for Ethereum Classic

json/src/spec/params.rs

@@ -35,6 +35,10 @@ pub struct Params {
 	/// Network id.
 	#[serde(rename="networkID")]
 	pub network_id: Uint,
+	/// Chain id.
+	#[serde(rename="chainID")]
+	pub chain_id: Option<Uint>,
+
 	/// Name of the main ("eth") subprotocol.
 	#[serde(rename="subprotocolName")]
 	pub subprotocol_name: Option<String>,
@@ -58,6 +62,7 @@ mod tests {
 			"homesteadTransition": "0x118c30",
 			"maximumExtraDataSize": "0x20",
 			"networkID" : "0x1",
+			"chainID" : "0x15",
 			"subprotocolName" : "exp",
 			"minGasLimit": "0x1388",
 			"accountStartNonce": "0x00"