images for readme

![massif-venn](https://user-images.githubusercontent.com/2317743/57045143-bb6e9400-6c3a-11e9-8479-ece10220b79e.png)

![massif](https://user-images.githubusercontent.com/2317743/57045160-c0334800-6c3a-11e9-8b77-d96e9183cb75.png)

![massif-header](https://user-images.githubusercontent.com/2317743/58094890-b51b6a00-7b9f-11e9-8504-4ae553ba1ed2.png)

 github image hosting hack 🤙

