title: multiBarChart (nvd3) in rCharts is not displaying
body: <p>I am using <a href="http://ramnathv.github.io/rCharts/" rel="nofollow"><code>rChart</code></a> library for generating javascript plots directly from R statistical package. I am trying to compute <code>multiBarChart</code> but the plot seems to be blank.</p>
  
  <p><strong>EDIT</strong>
  What is more, none of examples from here displays on my computer:
  <a href="https://github.com/ramnathv/rCharts/blob/master/inst/libraries/nvd3/examples.R" rel="nofollow">https://github.com/ramnathv/rCharts/blob/master/inst/libraries/nvd3/examples.R</a>
  all examples are blank. Also some1 has a similar problem here and refers maybe to proxy:<a href="https://github.com/ramnathv/rCharts/issues/624" rel="nofollow">https://github.com/ramnathv/rCharts/issues/624</a> .</p>
  
  <p>This code worked for my on my other computer.</p>
  
  <p>Any idea on what's going on and how to fix this?</p>
  
  <p>Objects to reproduce this bug:</p>
  
  <pre><code>WhoAndWhere2Viz &lt;- loadFromGithubRepo("cb754ba1e5b9542cdf982d1491c07099",
                     repo = "Museum",
                     user = "MarcinKosinski",
                     value =TRUE )
  </code></pre>
  
  <p>And a barchart itself</p>
  
  <pre><code> library(rCharts)
   n1 &lt;- nPlot( count ~ domena, group = "kto", data = WhoAndWhere2Viz,
                      type="multiBarChart")
         n1$addParams(dom = "myChart")
         n1$chart(color = c('brown', '#594c26', 'blue',  'green'))
   n1
  </code></pre>
  
  <p>My session info is</p>
  
  <pre><code>&gt; sessionInfo()
  R version 3.2.0 (2015-04-16)
  Platform: x86_64-pc-linux-gnu (64-bit)
  Running under: Ubuntu 14.04.2 LTS
  
  locale:
   [1] LC_CTYPE=pl_PL.UTF-8       LC_NUMERIC=C              
   [3] LC_TIME=pl_PL.UTF-8        LC_COLLATE=pl_PL.UTF-8    
   [5] LC_MONETARY=pl_PL.UTF-8    LC_MESSAGES=pl_PL.UTF-8   
   [7] LC_PAPER=pl_PL.UTF-8       LC_NAME=C                 
   [9] LC_ADDRESS=C               LC_TELEPHONE=C            
  [11] LC_MEASUREMENT=pl_PL.UTF-8 LC_IDENTIFICATION=C       
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods  
  [7] base     
  
  loaded via a namespace (and not attached):
  [1] tools_3.2.0
  </code></pre>