Update Elastica\Filter\HasParent

- _scope parameter was removed since ES 0.9
- Parent type can be specified by passing an instance of Elastica\Type
- Rewrite HasParentTest to use setUp/tearDown
Update Elastica\Filter\HasChild

- _scope parameter was removed since ES 0.9
- Child type can be specified by passing an instance of Elastica\Type
- Rewrite HasChildTest to use setUp/tearDown
Update changes.txt
Better coverage