ColorAxis Error Fixed [Update highcharts.py] , Heatmap Hover Color Error Fixed [Update common.py]

[ayamahmod]

1. The color axis always appears, even if it's not set in some charts like; line charts, spline charts, column charts, etc.
   I've fixed this error by updating highcharts.py .
   
2. The heatmap can't be updated to change the hover color like this url: http://jsfiddle.net/sgurhhm0/1/
   I always get an error when I try the following:
   self.H.add_data_set(yData,'heatmap',Data_Name,states={'hover': {'color': 'red'}})
   I've fixed this error by updating the Hover class in common.py

[ksolan]

Merged into v0.3.0. Thanks!!