FIXES #78649336 - heroku wont be able to make use of arrays fed to Setti...

PT: https://www.pivotaltracker.com/story/show/78649336

as https://github.com/railsconfig/rails_config states concerning arrays  in section heroku: 
"It won't work with arrays, though."
So for now just split the string..
somehow i think it would be the best to have just one settings.yml with all available options - as a kind of documentation. right now there are different options spread over every settings yml.  - the values get overwritten according to their env-files. so the best entry point could be settings.yml.
this is the reason why i put it here  -  left it blank with no specific reason...