Setup FE environment

[abossenbroek]

[] In case we want to set up specific eslint rules later: http://rahulgaba.com/front-end/2019/02/17/Use-custom-eslint-config-in-create-react-app-using-three-simple-steps-No-external-dependencies.html

[x] set up react

[x] set up redux starter kit

[x] set up saga

[x] config .gitignore