Created by: still-wait
- add vgg-ssd in voc and coco
- fix eval and infer in vgg-ssd
- fix data redaer with ssd
------------Local Test----------------
(1) In training all pass
mobilenet-ssd:
vgg-ssd in voc
vgg-ssd in coco
(2) In eval all pass
mobilenet-ssd: fix map:73.2
vgg-ssd in voc:
vgg-ssd in coco:
(3) In infer all pass
mobilenet-ssd:
vgg-ssd in voc:
vgg-ssd in coco:
