Add support for dropbox files
Add support for dropbox files

Fixes https://github.com/CookPete/react-player/issues/379

It turns out you can just replace www.dropbox.com with
dl.dropboxusercontent.com to access a shared file directly

Found in this handy article:
https://zapier.com/learn/how-to/generate-direct-dropbox-link/

CookPete/react-player,CookPete/react-player