Multi-user support.

[snakedye]

Currently, the images are shared among all users. This means that if two unrelated people send two labels images and want an analysis, instead of each of their image being analyzed, it will be the image A and B that will be analyzed.

Tasks:

• [ ] Create some kind of User class that aggregate his labels.

• [x] Update the /analyze route to be user specific.

• [x] Update the model diagram.

  Acceptance Criteria:

• A user cannot have access to the labels of another.

• The API should function the same way.

• Full test coverage.

[snakedye]

The response of /analyze should return:

{
  label_id: "...",
  form: "..."
}

[snakedye]

Proposal

Add a /new_label route. It'll return a unique label_id the frontend can use to modify a specific label.

@Youllou Opinions?