Support compass mixins

[amirabiri]

We are porting a large Ruby site to .NET with NancyFx & Compass.

We make extensive use of compass mixins. We realized Compass doesn't support that yet.

I've dug through the code and managed to hack it to get it to work, it's actually very simple. In SassCompiler.Initialize() I've modified the line:

scssOption = engine.Execute("{:cache => false, :syntax => :scss}");

To

scssOption = engine.Execute(@"{:cache => false, :syntax => :scss, :load_paths => [""C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/compass-0.12.2/frameworks/compass/stylesheets""]}");

Also digging around I notice the that Compass' SassCompiler is a copy of the SassAndCoffee.Ruby one. So I've also submitted a similar issue there.