[WIP] feature/refactoring preview

refactoring of the preview component and changes of the interface of the preview component to make it reusable for contacts

maybe it would be a better idea to refactor the base html layout into a responsive three column layout where you have to do less with js

__Tasks:__

- [x] adjust/refactor preview component
- [x] adjust components which use preview
- [x] move preview component to admin
- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none

Merge before this PR:
- https://github.com/sulu-cmf/SuluAdminBundle/pull/105