Break code into separate scripts, no webpack

- Broke up app.js into 5 scripts
- We have to manually include each script in index.html
- We have to pay attention to the order they load in

index.html

@@ -39,5 +39,9 @@
     </div>
     <img src="./assets/webpack.svg" />
   </body>
-  <script src="./src/app.js"></script>
+  <script src="./src/app/alert.service.js"></script>
+  <script src="./src/app/component.service.js"></script>
+  <script src="./src/app/utils/inputs-are-valid.js"></script>
+  <script src="./src/app/utils/parse-inputs.js"></script>
+  <script src="./src/app/app.js"></script>
 </html>