Images uploaded as assets are scaled down

When an image is uploaded into an asset folder, the image is scaled down to a thumbnail of at most 60x60 pixels. Only the thumbnail data is stored. The original image data is not stored, making it impossible to actually use the original image.

Instead, all uploaded asset data should at least be available as-is, untouched.

Steps to reproduce
1. login to the CMS
2. go to 'Documents' -> 'Assets'
3. select a root asset folder and choose 'Upload file' from the folder context menu
4. select an image
5. click 'OK' to upload the image to the asset folder

Expected behavior: the uploaded asset contains the original image data
Actual behavior: the uploaded asset only contains a scaled-down thumbnail version of the image; the original image is gone