Search: add `format` support for date range filter and queries

When the date format is defined in mapping, you can not use another format when querying using range date query or filter.

For example, this won't work:

```
DELETE /test

PUT /test/t/1
{
  "date": "2014-01-01"
}

GET /test/_search
{
  "query": {
    "filtered": {
      "filter": {
        "range": {
          "date": {
            "from": "01/01/2014"
          }
        }
      }
    }
  }
}
```

It causes:

```
Caused by: org.elasticsearch.ElasticsearchParseException: failed to parse date field [01/01/2014], tried both date format [dateOptionalTime], and timestamp number
```

It could be nice if we can support at query time another date format just like we support `analyzer` at search time on String fields.

Something like:

```
GET /test/_search
{
  "query": {
    "filtered": {
      "filter": {
        "range": {
          "date": {
            "from": "01/01/2014",
            "format": "dd/MM/yyyy"
          }
        }
      }
    }
  }
}
```

Same for queries:

```
GET /test/_search
{
  "query": {
    "range": {
      "date": {
        "from": "01/01/2014",
        "format": "dd/MM/yyyy"
      }
    }
  }
}
```

Closes #7189.
I see. I think it's a bit confusing that this parameter is optional on some methods (with a fallback to the instance parser) and compulsory in other methods. So +1 to fall back to dateMathParser here too