Image Details page: Replace 'View full image' button with a direct link to the full image

[StephenChan]

That is, we just link to the jpg/png itself. Benefits:

• We wouldn't have to worry about how the image is displayed on the page (EXIF orientation or not, beyond the borders of the rest of the page UI or not, etc.).
• It would only take a right click -> Save As to download the full image.
• We can get rid of a little bit of Javascript code on this page.