File deletions for thumbnails were failing becuase of the thumbnailPath changes.
File deletions for thumbnails were failing becuase of the
thumbnailPath changes.

Modifications made to check mediaThumbnailType and
thumbnailType to remove the correct files upon deletion.

ramiroaraujo/cakephp-upload,josegonzalez/cakephp-upload,zynesis/cakephp-upload,silviolleite/cakephp-upload,Phillaf/cakephp-upload,amstegraf/cakephp-upload