[FEATURE] added listener for currency select

__Requires:__
- https://github.com/sulu-cmf/SuluSalesCoreBundle/pull/21

__Tasks:__
- [x] done
- [x] got feedback

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none

empty?