Fix a bug in album art detection

New album art files were not being assigned to albums and copied into the appropriate location.

Normally, the scanner determines what album a certain art file is for by looking for files in the same directory as the art file and pulling the correct `album_id` from the database.

The database query was using `LIKE 'home/icecast/ocr-all/AlbumName/%'` and was not finding any matching `album_id` because the query was missing the leading slash in the directory name.

This patch will send the directory name with the leading slash in the query, allowing the database to return the appropriate `album_id` for album art.