removed container from SuluContentAdmin
added security check for webspace navigation items
added hasPermission method to SecurityChecker, to ask for permissions without throwing an exception
updated SuluContentAdmin to new SecurityCheckerInterface
secured media navigation
secured roles navigation item
secured permission tab in contact section
reconfigured admin classes to be only loaded in admin context
Merge pull request #577 from sulu-cmf/enhancement/secured-navigation

Secured webspaces, roles and collections in admin navigation