Turbo add enhancement - grouping by type (staged, modified, untracked)

[sfabrizio]

From @alancampora on September 21, 2016 22:1

We would like to group them by type e.g:

"staging area"
green ( added files)

"modified files"
[] file1
[] file2
[] file3

"untracked files"
[] new file1
[] new file2

Copied from original issue: labs-js/turbo-commit#40