Convert .sass files to .scss

If I'm going to work on this theme at all, Sass files will need to be in .scss format. I don't do .sass :)

.scss is the way to go, anyway. Very similar to and compatible with plain old CSS, etc.

Also, I'm converting 2 space indentation to 4 space tabs in the .scss files, because that's how I roll. If that's an issue, I'll be a wee bit sad.