Added most common genre to all tracks (closes #34)

Resolved issue of there being multiple artists on a track and "manually
created" an undefined genre for artists that don't have a genre.

spotifyvis/templates/spotifyvis/user_data.html

@@ -17,10 +17,5 @@
             <p class="browsehappy">You are using an <strong>outdated</strong> browser. Please <a href="#">upgrade your browser</a> to improve your experience.</p>
         <![endif]-->
         <p>Logged in as {{ id }}</p>
-        <script src="{% static "spotifyvis/scripts/user_data.js" %}"></script>
-        <script>
-            sessionStorage.setItem('user_secret', "{{ user_secret }}");
-            getAudioFeatureData('instrumentalness', sessionStorage.getItem('user_secret'));
-        </script>
     </body>
 </html>