Add time_zone setting for query_string

Query String query now supports a new `time_zone` option based on JODA time zones.
When using a range on date field, the time zone is applied.

```json
{
"query": {
  "query_string": {
    "text": "date:[2012 TO 2014]",
    "timezone": "Europe/Paris"
  }
 }
}
```

Closes #7880.