Force title property for templates

Merge together with 

- [x] https://github.com/sulu-cmf/SuluWebsiteBundle/pull/72
- [x] https://github.com/sulu-cmf/SuluMediaBundle/pull/102
- [x] https://github.com/sulu-cmf/SuluTestBundle/pull/28
- [x] https://github.com/sulu-cmf/SuluContentBundle/pull/267
- [x] https://github.com/sulu-cmf/SuluSearchBundle/pull/19

__Tasks:__

- [x] test coverage
- [ ] gather feedback for my changes
- [x] submit changes to the documentation

__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes
| Fixed tickets | none
| BC Breaks     | Every template definition must now contain a property named `title`, therefore the tag `sulu.node.name` is not necessary anymore
| Doc           | https://github.com/sulu-cmf/sulu-docs/commit/536abca24d81a9cc4d1860ef5f177e58734a482f