Allow @import to work with files located in assets/ (rather than only stylsheets/)

Not sure if this is the right approach, but got it working for me ...

I'm using bower to manage my frontend packages and I've got it's components folder set to `vendor/assets` since I need it for both my js and css assets. But when I try to import something e.g `@import 'karma/defaults'` it's not picking the vendored file up since the asset path doesn't end with `stylesheet`.

Hmmmm am I doing this right?