Update to latest grunt-contrib-imagemin so that it won't fail to run on certain versions of npm (like those in MEAN 0.5.0 in GCE).
Update to latest grunt-contrib-imagemin so that it won't fail to run on certain versions of npm (like those in MEAN 0.5.0 in GCE).

Splaktar/firefly,Splaktar/firefly,nassor/firefly,gdg-x/firefly,nassor/firefly,gdg-x/firefly