title: Using literal month names with year in ramcharts
body: <p>Here is my code to generate barplot using rAmChart,</p>
  
  <pre><code>library(rAmCharts)
  amBarplot(x = "month", y = "value", data = dataset, 
                    dataDateFormat = "MM/YYYY", minPeriod = "MM",
                    show_values = FALSE, labelRotation = -90, depth = 0.1)
  </code></pre>
  
  <p>However, is there a way to use month names &amp; year in my x axis? I am trying to use MMM-YY formats. </p>
  
  <p>Sample dataset,</p>
  
  <pre><code> structure(list(value = c(11544, 9588, 9411, 10365, 11154, 12688
  ), month = c("05/2012", "06/2012", "07/2012", "08/2012", "09/2012", 
  "10/2012")), .Names = c("value", "month"), row.names = c(NA, 
  6L), class = "data.frame")
  </code></pre>
  
  <p>Thanks.</p>