Increase the jpg quality in rec2image

[ShiquanYu]

1. Modify jpg save quality to 100%
2. Add tqdm process bar

[ielenik]

There is no need to read-write jpeg
s = imgrec.read_idx(_idx)
_header, _img = mx.recordio.unpack(s)
image_path = os.path.join(id_dir, "%d.jpg" % imgid)
with open(image_path, mode='wb') as file: # b is important -> binary
file.write(_img)