bug 915317 - gccrashes model

Looks like this:
```
curl -s 'http://localhost:8000/gccrashes/json_data/product/WaterWolf/version/2.0/start_date/2014-01-30/end_date/2014-02-04' | python -m json.tool 
{
    "hits": [
        [
            "20140203000001", 
            111
        ]
    ], 
    "total": 1

```