Preset: Grunt

Fixes #742

Depends on: https://github.com/jscs-dev/node-jscs/pull/749
> "follow the conventions you see used in the source already."

Though all of the details are not in the style guide, a lot of the source code already abides by the google preset.

Plus, when creating .jscsrc files, as you know, it's always much easier to base a styleguide off of an existing preset and override what you don't need.