fix bug 984960 - enable new correlations in middleware+UI

You can replace this with the following which is slightly more readable and what we tend to do in other services now: 

```python
fields = (
    "total_for_sig",
    "total_for_os",
    "crashes_for_sig",
    "crashes_for_os",
    "in_sig_ratio",
    "in_os_ratio",
    "addon_id",
    "reason",
)
hits = [dict(zip(fields, row)) for row in sql_results]
```

Plus this way you can remove the ``hits = []`` line before the SQL query.