Tickets/dm 1662

Hi Mario, 
 What is confusing here for me: 
- config.Darwin and config.Linux are in ups/ directory so I first thought it was eups configuration files.
- these both files are nearly the same, it's difficult to quickly see the difference between them.
An other solution would be to overload the prep function and apply a patch to the "config" file depending on the OS. This may look undertandable to future maintainers?