Minify sprockets.js

desc "Minify the javascript output by sprockets"
task :minimize_js => :environment do
  begin
    File.new("public/sprockets.js")
  rescue
    Rake::Task['sprockets:install_script'].invoke
  end

  require "lib/js_minimizer"
  js = IO.readlines("public/sprockets.js", '').to_s

  File.open("public/sprockets.js", 'w') do |file|
    file.write(JSMin.minimize(js))
  end
end