Fix bug in 2c0feaf94 that caused all the assets on the /uploads?mode=gallery
page to show the same source. The loop clobbered the `@upload` variable
such that the value from the last iteration was used by all assets.
Fix a bug where images on the My Uploads page would link to the wrong
upload. If an image had been uploaded by multiple users, then it would
link to the first upload belonging to the first person to upload the
image. This would lead to an Access Denied error when you tried to open
the upload.
Also fix a bug where uploads on the My Uploads page were ordered
incorrectly. They were ordered by most recent asset first, rather than
most recent upload first. This meant if you uploaded an image someone
else had already uploaded, then it would appear behind your other more
recent uploads.
