multiple bugs in context with homepage and preview

__Tasks:__

- [x] enable save after remove block
- [x] remove delete from toolbar on homepage
- [x] when on homepage click on homepage in navigation form and preview stays open
- [x] adjust routes for content/homepage to fix bug with changing languages
- [x] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| Tests pass?   | yes
| Fixed tickets | none
| Doc           | none

__Merge before this PR__
- https://github.com/sulu-cmf/SuluAdminBundle/pull/100
- https://github.com/sulu-cmf/SuluPortalBundle/pull/11