* Some uppy server -> companion renames
* Fix typos
* Implement most of @goto-bus-stop's feedback
* Nuke Create React App readme
* An Companion -> A Companion
* Companion server -> instance
This was always mounting the dashboard DOM element into the current
React container element, but that's not always the right thing to do,
for example if the container element is a small element with `overflow:
hidden` or some `position: relative` style.
This patch allows you to do `target={document.body}` and the like, so
you can mount the dashboard element anywhere.
