feat: add Express, Router + Static files, Environment Config #1
feat: unify app structure #1
feat: add Mongoose and few code adjustments #1
feat: add all CRUD end-points for Users #1
feat: add all CRUD end-points for Groups #1
feat: add filters to fetch/read end-points #1
feat: add middleware validation #1
feat: change lib structure #1
feat: add assign user to group and group to user #1
Merge pull request #2 from martinjezek/1-add-working-demo

Add working demo with Relational DB approach