title: Sending HTTP request headers in C3.js to source URL
body: <p>I am using c3-angular.min.js. On client side, I have written a interceptor for adding authorization header to each request being sent to api server.
  All http request seems to have authorization apart from ones which are made through C3.js. as result, my charts receives 401 error. Not much documentation is available.</p>
  
  <p>how to add http request headers on requests made by c3.js.</p>
  
  <pre><code> $scope.config={
              bindto: '#div1_chart',
              data: {
                'x':'x',
                'types':{'count':'area'},
                'names':{'count':'hits/day'},
                'url':$scope.base_url,
                'mimeType':'json'
              },
              axis : {
                  x : {
                      type : 'timeseries',
                      tick : {
                  rotate: 45,
                  multiline: false,
                        fit: false,
                        format : $scope.format 
                      },
                height:100
                  }
              }
          };
  $scope.showGraph = function() {
      $scope.chart = c3.generate($scope.config);     
  }
  </code></pre>