Add support for Grunt

[Joneser]

This module should also be made available to projects who use Grunt as their build tool.

Most likely a new module should be created for this in order to keep the grunt and gulp config separate (possibly have a standalone module for the core functionality and then modules for different build tools).

[prayerslayer]

Shameless self-plug: symdiff has the core functionality already separated in different modules you could reuse.