title: dc.js x-axis will not display ticks as months, shows decimals instead
body: <p>I'm building a bar chart using dc.js, and want the x-axis to list the 12 months of the year.</p>
  
  <p>So far, I have it rendering showing the first tick as a time of day (06 PM), and all subsequent ticks as decimals (thousandths).</p>
  
  <p>I saw a similar question (<a href="https://stackoverflow.com/questions/21392997/dc-js-x-axis-hour-labels-appear-as-thousandths#_=_">https://stackoverflow.com/questions/21392997/dc-js-x-axis-hour-labels-appear-as-thousandths#<em>=</em></a>), but the answer involved converting milliseconds to larger units, which isn't possible with months (that I know of).</p>
  
  <p>Here is my code.  Thanks in advance for the help.</p>
  
  <pre><code>var parseDate = d3.time.format("%m/%d/%Y").parse;
  
  data.forEach(function(d) {
      d.date = parseDate(d.weekStart);
      d.month = d.date.getMonth();
  });
  
  var monthDim = ndx.dimension(function(d) {return d.month;});
  var milesByMonth = monthDim.group().reduceSum(dc.pluck('miles'));
  //set range for x-axis
  var minDate = dateDim.bottom(1)[0].date;
  var maxDate = dateDim.top(1)[0].date;
  
  var barChart  = dc.barChart("#myBarChart"); 
  barChart
      .width(800).height(200)
      .margins({top: 10, right: 10, bottom: 20, left: 60})
      .dimension(monthDim)
      .group(milesByMonth)
      .gap(40)
      .transitionDuration(1500)
      .yAxisLabel('Miles Per Month')
      .renderHorizontalGridLines(true)
      .x(d3.time.scale().domain([minDate,maxDate]))
      //.x(d3.scale.ordinal())
      //.xUnits(dc.units.ordinal)
      //.x(d3.time.scale().domain([new Date(2012, 0, 1), new Date(2012, 11, 31)]))
      //.round(d3.time.month.round)
      .elasticX(true)
      .elasticY(true);
  </code></pre>