Convert backend code to ES modules

Bundling code now with Rollup for its flat bundling and tree shaking
support. Front end code still goes through Webpack for browser support.

lib/server.js

@@ -18,9 +18,9 @@
  */
 "use strict";
 
-const fs = require("fs");
-const http = require("http");
-const https = require("https");
+import fs from "fs";
+import http from "http";
+import https from "https";
 
 let server, listener;
 
@@ -48,7 +48,7 @@ function closeServer(timeout, callback) {
   });
 }
 
-function start(port, networkInterface, ssl, _listener, onConnection) {
+export function start(port, networkInterface, ssl, _listener, onConnection) {
   listener = _listener;
 
   if (ssl) {
@@ -76,7 +76,7 @@ function start(port, networkInterface, ssl, _listener, onConnection) {
   server.listen(port, networkInterface);
 }
 
-function stop() {
+export function stop() {
   return new Promise((resolve, reject) => {
     setTimeout(() => {
       reject(new Error("Could not close server in a timely manner"));
@@ -84,6 +84,3 @@ function stop() {
     closeServer(20000, resolve);
   });
 }
-
-exports.start = start;
-exports.stop = stop;