Start of shim for desktop payments (bug 1100998)

@muffinresearch r?

Not a very exciting patch but this gives me ideas for all the other bugs we need to file :) I figured it worth kicking off with a smaller patch.
Give the window object do we need to worry about node? I'm wondering if we could ditch the requirejs dep and just work with the namespacing.

We could also use a function to DRY up the namespacing.

e.g: http://jsbin.com/likisafeci/1/edit?js,console (based on yui's old namespacing function).