Changed child cardinality of andX and orX to 1..*

In case of a single child the composite constraint will not create a
composite node, but use the child directly.

In case of having more than 2 children, the composite constraint will
append additional constraints as required.
Merge pull request #329 from dantleech/qbv2_composite_cardinality

[QueryBuilder] Changed child cardinality of andX and orX to 1..*