Fix problem which is data of array model removed when $listOfFields was empty.

I defined models like below.
* Model A(based on DboSource)
* Model B(based on ArraySource)
* Relation: Model A belongsTo Model B

I encountered problem like below.
When I called `A-> find('all')` with `A->recursive = 2`, `ArraySource:: queryAssociation()` was called with `$queryData['fields']` which had fields related model A.

Because passed fields in `ArraySource::read()` were not existed in model B, `$listOfFields` in `ArraySource::read()` was empty. Therefore `ArraySource::read()` returned empty array.