Add spec for behaviour of NoLineBreaksValidator and nil values
Example for Bugfix in this commit. https://git.codecoop.org/schleuder/schleuder3/commit/3ba5ca114fd53ef78a324fe724a0400943a1c034
Example for Bugfix in this commit. https://git.codecoop.org/schleuder/schleuder3/commit/3ba5ca114fd53ef78a324fe724a0400943a1c034