Create a participant

{
    "participant": {
        "active": true,
        "checked_in_at": null,
        "created_at": "2015-01-19T16:54:40-05:00",
        "final_rank": null,
        "group_id": null,
        "icon": null,
        "id": 16543993,
        "invitation_id": null,
        "invite_email": null,
        "misc": null,
        "name": "Participant #1",
        "on_waiting_list": false,
        "seed": 1,
        "tournament_id": 1086875,
        "updated_at": "2015-01-19T16:54:40-05:00",
        "challonge_username": null,
        "challonge_email_address_verified": null,
        "removable": true,
        "participatable_or_invitation_attached": false,
        "confirm_remove": true,
        "invitation_pending": false,
        "display_name_with_invitation_email_address": "Participant #1",
        "email_hash": null,
        "username": null,
        "attached_participatable_portrait_url": null,
        "can_check_in": false,
        "checked_in": false,
        "reactivatable": false
    }
}