ProjectGroup read permission constrains

NC-66
Creation and deletion of ProjectGroups

NC-66
Mutation of ProjectGroups

NC-66
Enforce auth for project group endpoint

NC-66
Include url in user  resourcerepresentation

NC-68
Loose restrictions on users endpoint

NC-68
Merge branch 'feature/nc-66' into 'develop'

ProjectGroup CRUD, NC-66

This doesn't implement adding/removing projects from project groups, to be implemented in NC-84
Extended user model with additional fields

- NC-85
- made user model rw through rest
Fixed admin view of a custom user model
Extended user management via REST

- NC-85
- additional fields
- write support for staff users
Add a support for getting data of the current user

- NC-85
- Rewrite a call to /users/current to user's uuid
Fixed permission check for staff status
Added line ending
Refactor admin permission
Merge branch 'feature/nc-85' into 'develop'

Feature/nc 85
Updated release notes
Hotfix for anonymous user
Updated release notes
Extended user model and filtering by civil_number

- NC-87
Added user filtering to project permissions.

- NC-87