Zergpool 0 bitcore estimates with zergpoolplus
Maybe some kind of fallback?

![image](https://user-images.githubusercontent.com/1230402/39518318-de0f0672-4e02-11e8-9522-92e40510495f.png)

![image](https://user-images.githubusercontent.com/1230402/39518399-21fc583a-4e03-11e8-85c7-e1db9fcc54d6.png)
