Cleanup dependencies

[dimaip]

If somebody has some spare time, would be nice to resolve these warnings at some point:

[markusguenther]

We have one warning actually regarding the react-codemirror and this could not be resolved. There is actually no new version. Otherwise I need to adjust this package and trigger Jet Wadson.

[markusguenther]

Created a PR for react-css-themr to be react 16 compatible. Then this warning will be also gone :)

javivelasco/react-css-themr#88

[dimaip]

This issues is outdated