LESS basics

Added LESS support in GruntJS and "LESSified" the stylesheets. Also created a concatenated file called `footable.all.css` as well as `.min` versions of all CSS, as that's easily done in the GruntJS build task.

Just run `grunt less` if you want to just generate CSS, or use `grunt` to do everything. You can also run `grunt watch` and it will generate development (non-min) versions of CSS on the fly when you update a LESS file.