Add possibility to customize the threshold value
Gruntfile is now Gruntfile.js

( https://github.com/gruntjs/grunt/commit/26f304a36c50d748dd4b4c69c112430cfd4d67c2 )

Signed-off-by: Loïc Mahieu <mahieuloic@gmail.com>
Grunt v4 migration

Signed-off-by: Loïc Mahieu <mahieuloic@gmail.com>
ugifly

Signed-off-by: Loïc Mahieu <mahieuloic@gmail.com>