It should be possible to pass relevant props to the `Popper`

[idanen]

When updating this in our project we discovered that the popper is added to different positions of the document.
In previous version (we used 0.28.2) it was added closer to the body, but now it is added near the reference element.
This caused a regression for us that caused the popper to be hidden (when parent has overflow: hidden).
I noticed that Popper allows passing a prop called positionFixed which addresses exactly such an issue.
The same prop would also help solve #1246

Expected behavior

Being able to pass props to Popper

Actual behavior

Only some props are exposed

Steps to reproduce

Example: https://codesandbox.io/s/o7mqjjww29
Notice that the popper is hidden because the containing parent has overflow: hidden