Bug fix: make export example work on localized Linux systems

Adding a workaround for an OCC bug which causes the examle at 'src/examples/Level1/OCAF/step_export.py' to fail in a localized Linux environment. Fixes this issue: https://github.com/tpaviot/pythonocc/issues/67

(check twice before accepting - this is my first contribution to an open source project)