Query DSL: Fuzzy query support for numeric / date types

[kimchy]

Support the notion of fuzzy query for numeric types and dates. fuzzy query on a numeric field will result in a range query "around" the value using the min_similarity value. For example:

{
    "fuzzy" : {
        "price" : {
            "value" : 12,
            "min_similarity" : 2
        }
    }
}

Will result in a range query between 10 and 14. Same applies to dates, with support for time format for the min_similarity field:

{
    "fuzzy" : {
        "created" : {
            "value" : "2010-02-05T12:05:07",
            "min_similarity" : "1d"
        }
    }
}

In the mapping, numeric and date types now allow to configure a fuzzy_factor mapping value (defaults to 1), which will be used to multiply the fuzzy value by it when used in a query_string type query. For example, for dates, a fuzzy factor of "1d" will result in multiplying whatever fuzzy value provided in the min_similarity by it. Note, this is explicitly supported since query_string query only allowed for similarity valued between 0.0 and 1.0.