[FEATURE] SmartContent implements pager

Smart Content implements a pager

- [x] test coverage
- [ ] gather feedback for my changes
- [x] submit changes to the documentation

__Depends:__

- https://github.com/sulu-cmf/sulu/pull/200
- https://github.com/sulu-cmf/SuluWebsiteBundle/pull/37

__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | hopefully
| Fixed tickets | 
| BC Breaks     | none
| Doc           | not yet__Tasks:__