Ok.sendFile(inline = false) now quotes the file name - Fixes #941

I spotted an issue downloading files in Firefox that I was serving with Ok.sendFile(inline=false) when there were spaces in the file name - because thefile name (in the header) was not quoted.

So I've created an issue to track this https://play.lighthouseapp.com/projects/82401-play-20/tickets/941-oksendfile-with-inlinefalse-and-a-space-in-the-filename-does-not-download-on-firefox-correctly and have fixed in in my branch.

It's a very simple change, as you can see.