Added HTML5 Image Uploader

[kresty]

very cool Thank you for doing that!

I'd been thinking about it for a while (like maybe writing something even), because I was getting tired of the Flash prompts... but then it occurred to me that maybe someone'd already done it... Sure enough, HTML 5 uploads already existed, just needed to make them work.

What I'm not sure about is why it thinks the Flash version is "preferred".  I'd like to fix everyone's defaults, but I'm not quite sure how to do that.  Of course I only spent a few minutes on the problem, so maybe it's not hard.