title: graphs from Altair are not displaying
body: <p>On Ubuntu x64, I just freshly installed Anaconda 3.</p>
  
  <p>I then installed <code>altair</code> via <code>conda</code> per <a href="https://github.com/ellisonbg/altair" rel="nofollow">these directions</a>. Then I run the example code:</p>
  
  <pre><code>from altair import *
  population = load_dataset('population')
  
  Chart(population).mark_bar().encode(
      x='sum(people)',
  ).transform_data(filter="datum.year==2000")
  </code></pre>
  
  <p>The code runs, but nothing happens. I expected a page would open in the browser perhaps, like <code>bokeh</code> does. To be safe, I also ran <code>jupyter notebook</code> in the background and re-running the code - no difference.</p>
  
  <p>Please let me know if there's more information you need about my environment.</p>