Problematic dependency on `create-react-app`

[Marc]

Describe the bug
GK's initial PR (#64) bumped eslint and caused make test_webapp to fail. This was due to eslint needing to be pinned to 5.6 by create-react-app. This dependency is weird and we shouldn't ignore eslint updates because of it.

Expected behavior
Be able to update eslint (and others).

Additional context
This can probably be solved by ejecting the app.