After mulling it over, I think @alexgibson's suggestion of creating an all-encompassing image library is the way to go. @nburka is right - if `initHighResImages()` is called prior to `init_platform_imgs()`, an additional HTTP request will be made (each time `src` is set). Though it seems `init_platform_imgs()` is always called first as things currently stand, it would be much better to explicitly control execution order.

I don't think there's anything wrong with `init_platform_imgs()` being aware of/calling in to the `.HighRes` functions, as that's a more specialized use case. The (very slick) `src=""` part of the selector in `initHighResImages` does a nice job of handling any images that may have already been processed.

I'm cool with the `Mozilla.ImageHelper` namespace containing all image related stuff - high res, platform, and whatever else may come (responsive?).

@nburka - what do you think? Any concerns of suggestions?