use parse_url to verify dn, because filter_var has issues with special chars
Add test on adding bookmark with URL containing umlaut
Does not relate to this issue (different code path, not covered by tests
yet), but still it is a good addition.
Dependency Injection for user and db is used througout the controllers
The Routing features a consistent rest api
The Routing provides some legacy routes, so that for exampe the Android Bookmarks App still works.
There is a publicly available api that provides access to bookmarks per user.
(This is usefull in connection with the WP Plugin https://github.com/mario-nolte/oc2wp-bookmarks)
