Customize behaviour when identifies that the browser is Safari.

[gabrielrtakeda]

Hello everyone!

I want to customize the behaviour when the browser is Safari. Everybody knows that the Safari isn't support the a[download] attribute yet and, i want to handle the behaviour more customizable. For that, I implemented a simple solution for, just passing an option parameter to the download function but i'm in doubt about the flexibility and customizability for that solution.

I'll send a PR but discussion is opened! Best regards.