Exclude dotfiles automatically

[mxstbr]

dotfiles (files starting with a ., e.g. .htaccess) cannot get requested by a browser, results in a 403 error. (src: https://support.hostgator.com/articles/403-forbidden-or-no-permission-to-access) So putting them in an appcache manifest doesn't really make sense. Would be nice if this plugin excluded all dotfiles automatically.

Great work on this plugin, absolutely love it!

[crossRT]

Hey @lettertwo thanks for creating this awesome webpack plugin. It saves my day. =)
Anyway, it would be appreciated if you could excluding macOS .DS_store by default.