.jscsrc indentation clenup

The `.jscsrc` JSON file was using mixed tabs and spaces for indentation, this pull request fixes all indentation to spaces per the spec.

See also: JSON and YAML files should use spaces not tabs for indentation http://yaml.org/spec/1.2/spec.html#id2777534

p.s. Not sure why any of the validators/linters did not pick this up, will dig around that as I continue exploring the Compass repo :wink: