[FEATURE] Introduce different forms for product types

Depends on https://github.com/sulu-cmf/sulu/pull/236 and https://github.com/sulu-cmf/sulu/pull/237

__Tasks:__

- [ ] test coverage
- [ ] gather feedback for my changes
- [ ] submit changes to the documentation
- [ ] abstract type maps from javascript code
- [x] check postAction when not existing product ids are passed
- [ ] check if parent and variant are the same object

__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes
| Fixed tickets | none
| BC Breaks     | none
| Doc           | none