Feature/items


included item-table component for managing items in an order

__Tasks:__
- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | i hope so
| Doc           | none


__Requires:__
https://github.com/sulu-cmf/SuluSalesCoreBundle/pull/1
https://github.com/sulu-cmf/SuluSalesCoreBundle/pull/2