Improve _showDownloadBtn method

[adi130987]

Change request from Marko:

_showDownloadBtn: function(file) {
         var newFile = _.get(file,'file_name');
         if ((file && typeof file.path === 'string' && file.path !== '') || newFile) {
           return true;
         }
         return false;
       }

this will prevent the new uploaded file shown at the bottom of the list from overflowing its container
because it doesnt get that only-selected class added on