Add SCSS version of datepicker CSS

Hi there,

Great work with the date picker. I patched up the Less to work with a project, so I figured it might be useful for others.  It works with Thomas McDonald's [bootstrap sass](https://github.com/thomas-mcdonald/bootstrap-sass).

I see you're working on adding range picker functionality (which I need too), let me know if you're cool with this and I'd be happy to dig into / convert stuff on that too.