title: HighCharts xAxis - tickInterval for month
body: <p>Am trying to plot spline graph for the <em>no of passed/failed testcases</em> and grouping them based on <strong>hour/date/month/year</strong> and I am getting this value as irregular series <em>(i.e) if its hours, datas won't be available for all 24 hours. Its the same case for other groupings</em>. As the datas are irregular need the x-axis tick interval to be month vice, Have tried using the dateTimeLabelFormats, It didn't help me much as its only formats the label.</p>
  
  <p>All i need is the tickInterval needs to be month vice and both date&amp;time in tooltip.</p>
  
  <p>Sorry that i won't be able to post data/fiddle as am using this HighCharts in an BI tool(SpagoBI) and it requires templates.</p>
  
  <p>Thanks in advance.</p>