title: Displaying ITime values as.character in ggplot2
body: <p>I'm plotting a histogram of an <code>ITime</code> variable, and I want the x-axis ticks to be displayed in the <code>as.character</code> value if the x-variables. By default they are just represented as the number of seconds since 0:00. How can I accomplish this?</p>
  
  <pre><code>make.time &lt;- function(x){
          mins &lt;- sample(1:59, 1)
          if(mins &lt; 10) mins &lt;- paste0('0', mins)
          paste0(sample(1:23, 1), ':', mins)
  }
  
  
  data.table(x = sample(1:100, 50, T), 
             time = as.ITime(replicate(50, make.time()))) %&gt;% 
        ggplot(aes(time)) + geom_histogram()
  </code></pre>