Automatically combine small categories in a pie chart?

For example, here is a pie chart with 5 categories: http://jsfiddle.net/Lz41ow5c/. I would like to set a threshold so that the smallest categories are combined into an "Other" category like this (e.g. if they are less than 15% of the total): http://jsfiddle.net/jdd5aj6u/2/

I saw that there was a label threshold (http://c3js.org/reference.html#pie-label-threshold), but is there something similar for actually grouping data below a threshold?

Thanks!