Move finished codelab code and fix paths (#1337)

* Move the finished version of the codelab

This moves the finished version of the codelab to
app-completed so it's at the same level as the starting
app code.

* Fix paths to be relative

The paths for blockly files and media were absolute, which would
break if you ran it from any directory that wasn't identical.

demos/codelab/app-complete/index.html

@@ -60,10 +60,10 @@
     </div>
   </main>
 
-  <script src="/blockly_compressed.js"></script>
-  <script src="/blocks_compressed.js"></script>
-  <script src="/javascript_compressed.js"></script>
-  <script src="/msg/js/en.js"></script>
+  <script src="../../../blockly_compressed.js"></script>
+  <script src="../../../blocks_compressed.js"></script>
+  <script src="../../../javascript_compressed.js"></script>
+  <script src="../../../msg/js/en.js"></script>
 
   <script src="scripts/music_maker.js"></script>
   <script src="scripts/sound_blocks.js"></script>

demos/codelab/app-complete/scripts/main.js

@@ -79,7 +79,7 @@
   enableMakerMode();
 
   Blockly.inject('blockly-div', {
-    media: '/media/',
+    media: '../../../media/',
     toolbox: document.getElementById('toolbox'),
     toolboxPosition: 'end',
     horizontalLayout: true,