Add `path` method to `Caskroom` and `Cache`.

Library/Homebrew/cask/lib/hbc/cache.rb

Library/Homebrew/cask/lib/hbc/cask_loader.rb

Library/Homebrew/cask/lib/hbc/caskroom.rb

Library/Homebrew/cask/lib/hbc/cli/cleanup.rb

Library/Homebrew/cask/lib/hbc/cli/doctor.rb

Library/Homebrew/cask/lib/hbc/download_strategy.rb

Library/Homebrew/cask/lib/hbc/dsl.rb

Library/Homebrew/cask/lib/hbc/locations.rb

Library/Homebrew/compat/hbc/caskroom.rb

Library/Homebrew/test/cask/cask_spec.rb

Library/Homebrew/test/cask/cli/uninstall_spec.rb

Library/Homebrew/test/cask/installer_spec.rb

.../test/support/helper/spec/shared_context/homebrew_cask.rb