Picture article

Hi!

@mathiasbynens, @andreasbovens, @brucelawson & @zcorpan
As discussed (and fashionably late, sorry about that) here's the article I wrote about the picture element.

Cheers :)
Yoav

(Quick tip: the `(v=vs.85)` part of MSDN URLs like this can just be omitted, as can the `.aspx` suffix. `http://msdn.microsoft.com/en-us/library/windows/desktop/hh707223` works too.)