CLI: preserve history on start (#12)

* Don't wipe scrollback history on start

When using sirv together with some watching rebuilder like rollup (e.g. in svelte framework), sirv's wiping of the scrollback buffer makes it impossible to access build warnings.

* update comment

packages/sirv-cli/boot.js

@@ -62,7 +62,7 @@ module.exports = function (dir, opts) {
 			if (err) throw err;
 			if (opts.quiet) return;
 
-			clear(); // wipe screen
+			clear(true); // wipe screen, but not history
 			let { local, network } = access({ port, https });
 			stdout.write('\n' + PAD + colors.green('Your application is ready~! 🚀\n\n'));
 			isOther && stdout.write(PAD + colors.italic.dim(`➡ Port ${opts.port} is taken; using ${port} instead\n\n`));