Journal changes

https://trello.com/c/i3z2hJ7d/14-journal-%C3%A4nderungen

@tnt on Trello it says "Erstellt am nicht benötigt" under form changes, do you mean we should remove this column on the index?

I also changed the system test to use the assert_text / assert_link etc. shortcuts provided by Capybara which give nicer error messages.