[FEATURE] smart content data-source selection

smart content data-source selection:

__Tasks:__

- [x] test coverage
- [ ] gather feedback for my changes
- [x] submit changes to the documentation
- [x] implement new smart-content (https://github.com/massiveart/husky/pull/299)
- [x] fix filter / sorting
- [x] hide components (categories, present as)
- [x] add path to api (https://github.com/sulu-cmf/sulu/pull/107)
- [x] restore tree for smart-content
- [x] add webspace column (first column)
- [x] load tree (https://github.com/sulu-cmf/sulu/pull/109)

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | yes
| Fixed tickets | https://github.com/sulu-cmf/SuluContentBundle/issues/112 https://github.com/sulu-cmf/SuluContentBundle/issues/50
| Doc           | none