support for passing rpc credentials in with environment variables

app.js

@@ -87,14 +87,27 @@ app.runOnStartup = function() {
 
 	console.log("Running RPC Explorer for coin: " + global.coinConfig.name);
 
+	var rpcCredentials = null;
 	if (config.credentials.rpc) {
+		rpcCredentials = config.credentials.rpc;
+
+	} else if (process.env.RPC_HOST) {
+		rpcCredentials = {
+			host: process.env.RPC_HOST,
+			port: process.env.RPC_PORT,
+			username: process.env.RPC_USERNAME,
+			password: process.env.RPC_PASSWORD
+		};
+	}
+
+	if (rpcCredentials) {
 		console.log("Connecting via RPC to node at " + config.credentials.rpc.host + ":" + config.credentials.rpc.port);
 
 		global.client = new bitcoinCore({
-			host: config.credentials.rpc.host,
+			host: rpcCredentials.host,
-			port: config.credentials.rpc.port,
+			port: rpcCredentials.port,
-			username: config.credentials.rpc.username,
+			username: rpcCredentials.username,
-			password: config.credentials.rpc.password,
+			password: rpcCredentials.password,
 			timeout: 5000
 		});
 	}