Fixed a space in zern.py

Using a windows box, when trying to run this updated zern.py after your last changes had a space and two tabs on line 289, giving a compiler error of mixing tabs and spaces. That was both when installing using Win SDK 7.1, and when trying to import with py 3.3 64bit.
Merge pull request #1 from rockman507/patch-1

Fixed a space in zern.py