Enhance assets:clobber with css:clobber (#44)

rails/jsbundling-rails#52 (comment)

Author: Intrepidd

lib/tasks/cssbundling/clobber.rake

@@ -4,3 +4,5 @@ namespace :css do
     rm_rf Dir["app/assets/builds/[^.]*.css"], verbose: false
   end
 end
+
+Rake::Task["assets:clobber"].enhance(["css:clobber"])