Clean up code style and remove `.rubocop_todo.yml`.

Library/Homebrew/.rubocop.yml

Library/Homebrew/.rubocop_todo.yml

Library/Homebrew/brew.rb

Library/Homebrew/build.rb

Library/Homebrew/cmd/fetch.rb

Library/Homebrew/cmd/install.rb

Library/Homebrew/cmd/reinstall.rb

Library/Homebrew/cmd/style.rb

Library/Homebrew/cmd/tap.rb

Library/Homebrew/cmd/update-report.rb

Library/Homebrew/cmd/upgrade.rb

Library/Homebrew/cmd/uses.rb

Library/Homebrew/debrew.rb

Library/Homebrew/debrew/irb.rb

Library/Homebrew/dependency.rb

Library/Homebrew/dependency_collector.rb

Library/Homebrew/descriptions.rb

Library/Homebrew/dev-cmd/aspell-dictionaries.rb

Library/Homebrew/dev-cmd/audit.rb

Library/Homebrew/dev-cmd/bottle.rb