Adds Eyeglass support to Terraform

[kennethormandy]

This adds Eyeglass support to Terraform for .scss files, closing #103.

This PR also includes a (failing) test for .sass files, which works, but breaks regular .sass support in the process:

• If a .sass file is importing an Eyeglass module, it compiles successfully
• If a .sass file isn’t importing an Eyeglass module, there is an error during complication

Unclear whether this is a mistake in my configuration, or a bug.