retrieve:
Return the details about the given Theme id.

list:
List all Theme objects.

GET /api/v1/themes/6/
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "id": 6,
    "fr_label": "Construction",
    "en_label": "Building",
    "de_label": "Bau"
}