updated procfile and made server heroku compatible

Procfile

@@ -1 +1 @@
-web: cd backend && node app.js
+web: cd backend && npm install && node app.js

backend/app.js

@@ -108,6 +108,12 @@ function File(id, title, thumbnailURL, isAudio, duration, url, uploader, size, p
 // actual functions
 
 function startServer() {
+    if (process.env.USING_HEROKU) {
+        // default to port 80 on heroku
+        backendPort = 80;
+
+        // TODO: set config to port 80?
+    }
     if (usingEncryption)
     {
         https.createServer(options, app).listen(backendPort, function() {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "youtube-dl-material",
-  "version": "0.0.0",
+  "version": "3.5.0",
   "license": "MIT",
   "scripts": {
     "ng": "ng",