* add user onboarding workflow
* fix user editing (no edits of passwords of regular users after
onboarding)
* refresh HIBP breach cache in DB on app start-up
* display HIBP breach details
* fix request scheduling to prevent panics (this still needs some love..)
* fix middleware auth
* add TODOs
* update head.tmpl
* reword some error messages
* simplify protection of endpoints
* role discernment still occures in respective handlers
* db client needs to be passed into handlers as a global var now