title: Chart.js :set yAxis point to 0 when there is gap between two dates
body: <p>I'm using Chart.js and  in my xAxis I have an array of some dates with gaps like [2016:08:06,2016:08:10] and their matching values [20,40]</p>
  
  <p>the problem is that Chart.js are displaying days between the given array of dates. 
  I don't want to set my array to [20,0,0,0,40] since I have a gap of 3 days.
  how can I set autoatically their matching values in the yAxis to 0.</p>