[FEATURE] Added twig extension "navigation"

Added twig extension "navigation". which provide:

* `navigation`: Returns navigation for content node at given level
* `breadcrumb`: Returns breadcrumb for given node

__Tasks:__

- [x] test coverage
- [ ] gather feedback for my changes
- [x] submit changes to the documentation

__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes
| Fixed tickets | https://github.com/sulu-cmf/SuluContentBundle/issues/180
| BC Breaks     |  no
| Doc           | https://github.com/sulu-cmf/docs/blob/master/developer-documentation/300-webspaces/twig-extensions.md (full file)