Delete the previous cover image
nd only do changes if the new one was uploaded

Signed-off-by: Suki <suki@missallsunday.com>
Add a delete cover feature and show the current cover's humbnail if available

Signed-off-by: Suki <suki@missallsunday.com>
Make a few adjustments to get the right file
Add the correct path to the thumbnail image for file_exists()
delete the .htaccess file.

Signed-off-by: Suki <suki@missallsunday.com>