Fix copy&paste from sass-rails which uses sass

Here we should use SassC, that's whole point :)

Author: vimutter

lib/rails/generators/sass_scaffold.rb

@@ -1,4 +1,4 @@
-require "sass/css"
+require "sassc/engine"
 require "rails/generators/named_base"
 
 module Sass
@@ -7,7 +7,7 @@ class ScaffoldBase < ::Rails::Generators::NamedBase
       def copy_stylesheet
         dir = ::Rails::Generators::ScaffoldGenerator.source_root
         file = File.join(dir, "scaffold.css")
-        converted_contents = ::Sass::CSS.new(File.read(file)).render(syntax)
+        converted_contents = ::SassC::Engine.new(File.read(file)).render
         create_file "app/assets/stylesheets/scaffolds.#{syntax}", converted_contents
       end
     end