title: change height attributes of graph produced with rCharts for use with rshiny
body: <p>I am using rCharts to implement an interactive graph in rshiny. I am using the morris library
  Here is a minimal example of my problem:</p>
  
  <pre><code>## ui.R
  require(rCharts)
  shinyUI(pageWithSidebar(
    headerPanel("rCharts: Interactive Charts from R using morris.js"),
  
    sidebarPanel(
    ),
    mainPanel(
      showOutput("myChart", "morris")
    )
  ))
  
  require(rCharts)
  shinyServer(function(input, output) {
    output$myChart &lt;- renderChart({
      data(economics, package = 'ggplot2')
      econ &lt;- transform(economics, date = as.character(date))
      m1 &lt;- mPlot(x = 'date', y = c('psavert', 'uempmed'), type = 'Line',
                  data = econ)
      m1$set(pointSize = 0, lineWidth = 1)
      m1$addParams(dom = 'myChart')
      m1$params$width = 200
      m1$params$height = 200
      return(m1)
    })
  })
  </code></pre>
  
  <p>The height and width components work fine if the m1 object is not sent to shiny but they seem to be ignored after being processed by <code>renderChart</code>. I have resorted to a temporary fix using a style sheet:</p>
  
  <pre><code>.shiny-html-output.morris{
    height: 200px;
    width: 200px;
  }
  </code></pre>
  
  <p>Is there some option I am missing? For example in <code>plotOutput</code> in the <code>shiny</code> package you could
  stipulate: <code>plotOutput("plot2", height = "260px")</code> for example.</p>