This is deprecated API and will be dropped at some point, in favor
of projects shipping their own CSS.
Follow https://github.com/cockpit-project/starter-kit/blob/master/webpack.config.js
approach on how to use PF CSS.
Also:
* Replace extract-text-webpack-plugin with mini-css-webpack-plugin as
the former is deprecated: https://webpack.js.org/plugins/extract-text-webpack-plugin/#usage
* Upgrade PF module dependency
* Reduce the css files that are linked through webpack. Instead include
from the JS the CSS files and let mini-css-extract-plugin do the rest of
the work
Gave buttons IDs for ease of access, fixed `fit-to` testing to
better reflect purpose, and fixed occasional timing error in
`testSkipFrame` caused by call overlap
> warning: Warning: componentWillMount has been renamed, and is not
recommended for use. See https://fb.me/react-unsafe-component-lifecycles
for details.
* Move code with side effects to componentDidMount, and set initial
state in the constructor
