列出系统更新

用于获取系统更新的示例请求：

GET /api/system/v1/updates HTTP/1.1
Authorization: Basic abcefgMWE=
Host: zfssa.example.com:215
Accept: application/json

响应示例：

HTTP/1.1 200 OK
X-Zfssa-Appliance-Api: 1.0
Content-Length: 541
Content-Type: application/json

{
    "updates": [
    {
        "date": "Tue Aug 13 2013 17:47:32 GMT+0000 (UTC)",
        "href": "/api/system/v1/updates/nas@2013.08.13,1-0",
        "status": "previous",
        "version": "2013.08.13,1-0"
    },
    {
        "date": "Sat Aug 24 2013 17:54:23 GMT+0000 (UTC)",
        "href": "/api/system/v1/updates/nas@2013.08.24,1-0",
        "status": "current",
        "version": "2013.08.24,1-0"
    },
    {
        "date": "Sun Aug 25 2013 12:56:57 GMT+0000 (UTC)",
        "href": "/api/system/v1/updates/nas@2013.08.25,1-0",
        "status": "waiting",
        "version": "2013.08.25,1-0"
    }]
}