Proposed fix for #814

This is checking if the OS is MacOSX and trying to run some the non browser version of OpenRefine  if so.
I don't even know if there is a non browser client of the product but we should check at least if we want that version to run before trying to use it.
Anyway, reading the comment in the inside of the if, it seems that it doesn't work anyway.
I've tried this in MacOSX (not emulator) and #814 gets fixed with this.