xml template improvements

Implement missing XML Template Features, such as tags, title, multilingual flag, mandatory flag: 

__Tasks:__

- [x] test coverage
- [ ] gather feedback for my changes
- [x] submit changes to the documentation
- [x] extend xml schema
- [x] extend cache class gen
- [x] tags parsing
- [x] replace property access with tags
- [x] change ResourceLocatorController in ContentBundle (https://github.com/sulu-cmf/SuluContentBundle/pull/125)
- [x] implement mapper multilingual
- [x] change template dists in sulu-standard (https://github.com/sulu-cmf/sulu-standard/pull/68)
- [x] implement property title (translation keys) in content form (https://github.com/sulu-cmf/SuluContentBundle/pull/125 , https://github.com/sulu-cmf/SuluTagBundle/pull/31)
- [x] breadcrumb property access 
- [x] navigation property access (https://github.com/sulu-cmf/SuluWebsiteBundle/pull/15)
- [x] content title in form property access (https://github.com/sulu-cmf/SuluContentBundle/pull/125)


__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | no => https://github.com/sulu-cmf/SuluTestBundle/pull/10
| Fixed tickets | https://github.com/sulu-cmf/sulu/issues/76 , https://github.com/sulu-cmf/sulu/issues/75 , multilingual , mandatory
| Doc           | https://github.com/sulu-cmf/docs/blob/master/detail-specification/300-webspaces/DET-301-template-architecture.md