Json

Moving from requests with xml to requests with json.

When asking for photos inside a set, if the set contains only one photo, the answer is:
<rsp stat="ok"> 
	<photoset id="72157633253655952" primary="8347218260" owner="46299892@N00" ownername="jeromelebel" page="1" per_page="500" perpage="500" pages="1" total="1"> 
		<photo id="8347218260" secret="fe016e5aa8" server="8047" farm="9" title="photo.JPG" isprimary="1" /> 
	</photoset> 
</rsp>

which is transformed into:
{
    "photoset": {
        "id": "72157633253655952",
        "primary": "8347218260",
        "owner": "46299892@N00",
        "ownername": "jeromelebel",
        "photo": {
            "id": "8347218260",
            "secret": "fe016e5aa8",
            "server": "8047",
            "farm": 9,
            "title": "photo.JPG",
            "isprimary": "1"
        },
        "page": "1",
        "per_page": 500,
        "perpage": 500,
        "pages": 1,
        "total": "1"
    },
    "stat": "ok"
}

NSArray is missing into photoset.photo

To solve this problem, I request json, so I get this answer:
{
    "photoset": {
        "id": "72157633253655952",
        "primary": "8347218260",
        "owner": "46299892@N00",
        "ownername": "jeromelebel",
        "photo": [{
            "id": "8347218260",
            "secret": "fe016e5aa8",
            "server": "8047",
            "farm": 9,
            "title": "photo.JPG",
            "isprimary": "1"
        }],
        "page": "1",
        "per_page": 500,
        "perpage": 500,
        "pages": 1,
        "total": "1"
    },
    "stat": "ok"
}

Here there is no mistake.

The other benefit is to remove the xml parser. The code is lighter. But one issue is the json parser requires 10.7 or 5.0.

I added -[OFFlickrAPIContext defaultParameters]. If you don't like this pull request and you like this, I can create a pull request just for that.

Let me know.

I have no problem if you close this pullrequest without taking my commits.