Load images directly where they are used

[tjwelde]

Right now, all images are loaded in the index.jsx file. We can move this logic to the OneImage component, which will get the images from gaia on mount. The component will just get the image path as property.

[benpbenp]

I think this is a nice easy win for separation of concerns while still keeping a single place (index.jsx) for application state for the time being.

We need a username prop in addition to the path prop though.