Return an array where each entry is an object with this form:

{ source: "fitbit", name: "Fitbit", usernames: ["beau", "madprime"] }

GET /api/public-data/members-by-source/?source=direct-sharing-39
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Cache-Control: max-age=0, no-cache, no-store, must-revalidate
Content-Type: application/json
Expires: Tue, 07 Apr 2020 13:08:21 GMT
Vary: Accept

{
    "count": 48,
    "next": null,
    "previous": null,
    "results": [
        {
            "source": "direct-sharing-39",
            "name": "Quantified Flu",
            "usernames": [
                "madprime",
                "sarahwilliams",
                "Clifford_G_Andrew_PGP84",
                "padams89",
                "gsdcomo",
                "gerwitz",
                "medicfurby",
                "andyemcee",
                "mielghar",
                "Kimwhit",
                "sprague",
                "Taed",
                "kspersons",
                "phenylalanine",
                "gedankenstuecke",
                "wzwaag",
                "nbowen",
                "salbers12",
                "ericjdaza",
                "tejajustice",
                "mheffler",
                "mbpalladino",
                "Kate48230",
                "kgelineau",
                "jrandymac",
                "maximinio",
                "Agaricus",
                "hugooc",
                "decantrix",
                "Lovelee",
                "Horsesrunwild",
                "IonutMurariu",
                "kywildcat1954",
                "kelleymic",
                "husamia",
                "tchaber",
                "HiImDannyGanz",
                "kdgreis",
                "pawelgawel",
                "ajft",
                "vanilla_chief",
                "Explore360",
                "Coding_Lizard",
                "Judy323",
                "fury",
                "Nemesis25081",
                "Koush",
                "M_P",
                "carolinux",
                "katewac",
                "Iain",
                "uranusbean",
                "liubovv",
                "LongboatAline",
                "flin1",
                "ultimape",
                "angeliathatsme",
                "michaljamrich",
                "Misnowolf77",
                "TJHolland",
                "tedwyer1",
                "testuser1",
                "gusjan",
                "PetuniaWash",
                "kaya1976",
                "lbaldy",
                "Devis",
                "jasonj",
                "micky",
                "CalinGG",
                "vladm",
                "natalianorori",
                "naren",
                "Natalia_G",
                "herrberg",
                "synteny",
                "bence",
                "hleinone",
                "gln003",
                "grey",
                "davidjhall",
                "Buster88",
                "Nino",
                "solittlesofierce",
                "flixi67",
                "cheezerman",
                "Sophie",
                "rgllm",
                "anderstholen",
                "lynn",
                "Teal",
                "Epollux",
                "Henk_H",
                "biceroni",
                "JamesEye",
                "Luxyr",
                "PaulaH"
            ]
        }
    ]
}