[FEATURE] Functionality for converting the status of an order

now, a "created" order can be converted to status "confirmed"

__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/SuluAdminBundle/pull/159
https://github.com/sulu-cmf/sulu/pull/213