SSH, single stage face detector

Widerface result, by pyramid testing.

| Impelmentation     | Easy-Set | Medium-Set | Hard-Set |
| ------------------ | -------- | ---------- | -------- |
| Original Caffe SSH | 0.93123  | 0.92106    | 0.84582  |
| Our Model          | 0.93394  | 0.92187    | 0.83682  |

Pretrain model on [baiducloud](https://pan.baidu.com/s/1AoNAIq2pD1H58xuzoOIrIw) and [googledrive](https://drive.google.com/open?id=1r7FjiAFTb1jbdU-iee-s5s8BMyeSewOj)