First approach contact person option

Signed-off-by: DarioI <dario.incalza@litus.cc>
Forgot to commit Supplier

Signed-off-by: DarioI <dario.incalza@litus.cc>
Property name not necessary

Signed-off-by: DarioI <dario.incalza@litus.cc>
added nullable

Signed-off-by: DarioI <dario.incalza@litus.cc>
bugfix

Signed-off-by: DarioI <dario.incalza@litus.cc>
Added contactperson information to views

- added in the manage overview from all the suppliers
- added in the manage view with all the users for a certain supplier.

Signed-off-by: DarioI <dario.incalza@litus.cc>
Code update
Merge remote-tracking branch 'LitusProject/dev-contactperson'