Fix FunstionScore Query random_score without seed bug

[krzaczek]

Hi,

Quick fix for a random_score without seed. When we want to execute match all query with random sorting

$Query = new Elastica\Query();
$QueryFS  = new Elastica\Query\FunctionScore();
$QueryFS->setRandomScore();
$Query->setQuery($QueryFS);

{
    "query": {
        "function_score": {
            "random_score": []
        }
    }
}

This will fail in Elasticsearch because of "random_score": []:

{
    "query": {
        "function_score": {
            "random_score": {}
        }
    }
}

Should be like this :)
Added a test with empty seed to check if it workd in ES.

Pawel

[coveralls]

Coverage increased (+0.08%) when pulling 1b6a575 on krzaczek:fix-random-score into 591a74e on ruflin:master.

[ruflin]

Merged. Thx.