links -> contact_roles rather than roles

From https://bulletproofnetworks.github.io/kevlar-api-docs/#service-json:

```
{
    "links": {
        "roles": {
            "href": "https://manage.bulletproof.net/api/v4/roles/5,12,17,20",
            "ids": ["5", "12", "17", "20"],
            "type": "roles"
        }
    }
}
```

Production currently has:
```
{
    "created_at": "2013-12-20T12:15:25.000+11:00",
    "id": 11252,
    "links": {
        "contact_roles": {
            "href": "http://manage.bulletproof.net/api/v4/contact_roles/batch/102998%2F103008%2F198802%2F174408",
            "ids": [
                102998,
                103008,
                198802,
                174408
            ],
            "type": "contact_roles"
        }
    },
    "monitoring": true,
    "name": "olympus-avmh-web-01",
    "serviceid": "olympus-avmh-web-01",
    "state": "active",
    "updated_at": "2014-11-03T11:12:56.000+11:00"
}
```