Add a task to clear builds (#36)

Author: mibradev

lib/tasks/cssbundling/clean.rake

@@ -0,0 +1,8 @@
+namespace :css do
+  desc "Remove CSS builds"
+  task :clean do
+    rm_rf Dir["app/assets/builds/[^.]*.css"], verbose: false
+  end
+end
+
+Rake::Task["assets:clean"].enhance(["css:clean"])