Importing SVG icons with viewBox respected or with artboard that has correct height is not working
The issue is that when using `html-sketchapp-cli` (that uses your code more or less directly) to import svg icons, all my icons (200+) does not get correct width and height set. This means that it is not easy to just swap out an icon in a symbol in Sketch, resulting in pain for our designers. The symbol swapper will only allow to swap icons that has the exact same size.

When importing, I expect that the artboard or symbol size would be the same as the container or the SVG itself (for example 48px x 48px), but when importing, we get sizes like 45px x 45px or 43,5px x 43,5px or 43px x 41px.

This happens also when I manually drag and drop a svg into sketch. This does however NOT happen when doing the same in Figma or Framer. What gives? Is this purely a Sketchapp issue, or could this be handled by `html-sketchapp`?

**html-sketchapp version:** Latest

**minimal example:** https://gist.github.com/phun-ky/deb1579e2a108ab2cf6654f3d20d6cb0

**screenshot from the browser:** 
![image](https://user-images.githubusercontent.com/1714029/72439918-28659200-37a8-11ea-890e-7d560c0614e1.png)

**screenshot from Sketch:** 

![image](https://user-images.githubusercontent.com/1714029/72440766-c443cd80-37a9-11ea-864f-1e906ac21b19.png)
![image](https://user-images.githubusercontent.com/1714029/72440778-cad24500-37a9-11ea-9b4a-80f12d4315de.png)
