* added optional image to bookable item model

* added update method in serializer to handle new images

* linting

* remove update method for images

* added approved by field

* endpoint will now set approved by

* serializer will return full user object in approved_by_detail

* created test for approved by

* migration

* remove unnecessary code

* removed write-only field in approved-by context

* init

* format

* added richer reponse on post and put

* added to admin panel

* added filter for minute