retrieve:
Return the details about the given Category id.

list:
List all Category objects.

GET /api/v1/categories/
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "count": 6,
    "next": null,
    "previous": null,
    "results": [
        {
            "id": 5,
            "fr_label": "Communauté EPFL",
            "en_label": "EPFL community",
            "de_label": "EPFL Gemeinschaft"
        },
        {
            "id": 2,
            "fr_label": "Enseignement",
            "en_label": "Education",
            "de_label": "Bildung"
        },
        {
            "id": 1,
            "fr_label": "EPFL",
            "en_label": "EPFL",
            "de_label": "EPFL"
        },
        {
            "id": 8,
            "fr_label": "Evénements",
            "en_label": "Events",
            "de_label": "Veranstaltungen"
        },
        {
            "id": 4,
            "fr_label": "Innovation",
            "en_label": "Innovation",
            "de_label": "Innovation"
        },
        {
            "id": 3,
            "fr_label": "Recherche",
            "en_label": "Research",
            "de_label": "Forschung"
        }
    ]
}