Queue up generation of all regular image sizes, as soon as an image is uploaded.
Made /embed/file/<image> blocking with a timeout of 15 seconds, after which it redirects to the 'No preview available' image
On Image view page, the thumbnails in the sidebar were being vertically aligned in their container using JS. This was having inconsistent behaviour, because at time the alignment was happening before the image loads. This is fixed by aligning them both before loading and after loading.