Fix update of VariantGroup to not permit to associate Attribute Group in axis
Add exists and not exists predicate to use in Query
Update Attributes list to not display attributes used by VariantGroup
Add a boolean on the attributes of type groups to define there as Typology

When a group is defined as a typology of product, it will be proposed
in product editor to create it with these attributes
Merge pull request #832 from loiccouturier/master

Enhance Attributes