message: Warn if "yarn install" is required
diff: @@ -5,6 +5,12 @@ unless using_bundler
  exit(1)
  end
  +unless Dir.exist? '../node_modules'
  + puts "\nYou will need to run:".red
  + puts " yarn install\n\n"
  + exit(1)
  +end
  +
  source 'https://github.com/artsy/Specs.git'
  source 'https://github.com/CocoaPods/Specs.git'
  