Bothub logo not well aligned

**Description:**  
In the repository header, the Bothub logo is not vertically centered
![image](https://user-images.githubusercontent.com/39275274/59763671-78ab5e80-9270-11e9-80a2-5c685dde43ed.png)

> **Browser:** any  
> **OS:** any
> **Authenticated**: any
> **URL**: https://bothub.it/anybot