Add project<->user association

[mihow]

• Add many2many relationship between projects & users - make a new migration & commit file
• Auto assign a user to a project when they create it
• Expose the projects a user belongs to in the user profile API endpoint (/me)
• Update Django admin for projects so we can manually add users to a project until public UI is ready
• Add tests (current user added to project when it is created via the API)
• See possible UI for "My projects" section on top of home page Make it easier to find your project  #518

Follow-up tasks:

• Use the upcoming project edit screen for managing project members
• Full permission checks for access to projects and related data Add object-level permissions for Projects & related entities #219 Consider moving permissions to user object #354
• Add tests for permissions and access to different actions Rework project structure and clarify the collection concept #639
• Roles can come later (annotator, data processor, admin, etc)

[mihow]

See existing PR/branch #275

[mihow]

Step 0
Update project & /me endpoints (/me just shows project IDs) (/projects can filter by userID)

Step 1

Step 2

Step 3
see other follow-up tasks

[mohamedelabbas1996]

@mihow may be we can close this issue now, because we have implemented the tasks in the first part and we already have the follow-up tasks in this issue #624

[mihow]

Closed by #275 woohoo!