Add test for highlight problem with chxr values when you passed :axis_ran

[joel]

I add this test

it "with scaled values should provide the chxr good  values" do
  x_min, x_max, x_step = 0, 3, 1
  y_min, y_max, y_step = 0, 80, 10
  scale = [0,100]
  data = [[0,25,10,15],[50,60,80,30]]
  Gchart.line( :data => data,
    :encoding => 'text',
    :axis_range => [[x_min,x_max,x_step],[y_min,y_max,y_step]],
    :min_value => scale[0],
    :max_value => scale[1]).include?("chxr=0,#{x_min},#{scale[1]},#{x_step}|1,#{y_min},#{scale[1]},#{y_step}").should be_true
end

This test passed with success but it's not the expected behaviour

Expected behaviour must be

it "with scaled values should provide the chxr good  values" do
  x_min, x_max, x_step = 0, 3, 1
  y_min, y_max, y_step = 0, 80, 10
  scale = [0,100]
  data = [[0,25,10,15],[50,60,80,30]]
  Gchart.line( :data => data,
    :encoding => 'text',
    :axis_range => [[x_min,x_max,x_step],[y_min,y_max,y_step]],
    :min_value => scale[0],
    :max_value => scale[1]).include?("chxr=0,#{x_min},#{x_max},#{x_step}|1,#{y_min},#{y_max},#{y_step}").should be_true
end

[aderyabin]

I think that is not a problem, its a feature. Look at this code https://github.com/mattetti/googlecharts/blob/master/lib/gchart.rb#L500