Use the doctrine-extensions to generate url's

This way, we have a unit tested, and popular library creating url's for us.
It also fixes #662 Greek, cyrilic and other characters will work again.
Add bugfix to changelog.
Use behat/transliterator instead off doctrine-extensions

This library causes less overhead (doctrine is not needed as dependency)
and is currently being integrated in the doctrine-extensions.
(https://github.com/Atlantic18/DoctrineExtensions/pull/1079)
Update dependencies.

This was needed to download the behat/transliterator.