Remove missing (no longer used) workbook.scss processing

Author: Matthew McCullough

Rakefile

@@ -8,7 +8,6 @@ end
 task :test do
   sh 'bundle exec sass --style compressed _stylesheets/page.scss:_stylesheets/page.css'
   sh 'bundle exec sass --style compressed _stylesheets/home.scss:_stylesheets/home.css'
-  sh 'bundle exec sass --style compressed _stylesheets/workbook.scss:_stylesheets/workbook.css'
   sh 'bundle exec jekyll build'
 
 #  HTML::Proofer.new("./_site").run