Importing without specifying '.sss'

Currently, to import an .sss file, you have to specify the extension:

`@import 'base/vars.sss'

I think it would be nice if the following assumed it was an .sss file, similar to how Browserify/module bundlers assume the .js extension:

`@import 'base/vars'

You would still be able to manually specify .css (or other) extension.
