Add basic structure for products
Test product member product type.
Add tax category module.
Add tax category classes.
Add TaxCategoryIntegrationTest, but this will fail for now since deleting TaxCategories is not supported by the backend yet.
Add isFirst and isLast to PagedQueryResult, close #25.
Remove Category Categories companion class.
Replace scala category integration test by a Java implementation.
Rename PagedQueryResult.headOption to head.
Fix ProductImplTest.
WIP product classes.
Add CustomerGroup and Channel dummy for products, close #35, close #36
Add product classes.
Add missing builder for product data.
Add missing query classes for product data.
Add Base as base class.
Fix ProductImplTest.
Do not serialize object in Reference to JSON.
Fix ProductCrudIntegrationTest.
Create bundles for Java, Scala and Play Java, close #42.