Added a label group for Pie charts to prevent occlusion by slices.
Added a label group for Pie charts to prevent occlusion by slices.

hansmaad/chartist-js,chartist-js/chartist,cr3ative/chartist-js,chartist-js/chartist,hansmaad/chartist-js,cr3ative/chartist-js,gionkunz/chartist-js,chartist-js/chartist,gionkunz/chartist-js