Able to remove Seed file item

[vlagnar]

This might be a good item to add to allow for the file to be created without the seed.

function _write(cfb, options) {
var _opts = options || {};
/* MAD is order-sensitive, skip rebuild and sort */
if(_opts.fileType == 'mad') return write_mad(cfb, _opts);
rebuild_cfb(cfb);
if (_opts.noseed) cfb_del(cfb, "/\u0001Sh33tJ5"); <--------------- Added to allow for the file item not to be created!!!!
switch(_opts.fileType) {
case 'zip': return write_zip(cfb, _opts);
//case 'mad': return write_mad(cfb, _opts);
}