[BUGFIX] fixed issue with minimal quantity for shippments

__Tasks:__
- [x] adjusted warning labels
- [x] fixed for / id attributes in html 
- [x] fixed check for minimal quantity
- [x] added translations for warning
- [x] fixed issue with navigation
- [x] got feedback

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none