Revert "Mistakes fixed in Upload_model.php. Note the hard coded paths in assets/js/custom.js:135,140 and application/models/upload_model.php:21,29. They might need to change if picture upload doesn't work properly. Also, write folder permissions are needed for processing thumbnails"

This reverts commit 3f01e5612be8bf072ba8e7f71d3cb0c6dbb8ea22.