added context to navigation mapper
fixed interface of navigation mapper
implemented nav contexts test
implemented flat tests
implemented flatten navigation
implemented flatten navigation context
added content / flat to navigation twig extension
Merge branch 'develop' of git://github.com/sulu-cmf/SuluWebsiteBundle into feature/navigation-context
fixed if-style
fixed navigation code style
fixed testcases
removed unused code
Merge branch 'feature/navigation-context' into develop