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..
the reason for ENV here is, that these variables will be handed over on production by ENV also.
i wanted to make sure, that these tests happen under circumstances that are similar to those on production...
There is no spec existent, that tests the behavior of "Settings" itself.