Get Python with UNO path from an environment variable

Avis.py

@@ -42,7 +42,7 @@ class AvisOdt:
         renderer = appy.pod.renderer.Renderer(
            '%s/%s.odt' % (os.path.dirname(__file__), self.portal_type),
            {'avis': self}, tempFileName,
-           pythonWithUnoPath='/usr/bin/python2.6')
+           pythonWithUnoPath=os.environ.get('PYTHON_WITH_UNO_PATH'))
         renderer.run()
         # Tell the browser that the resulting page contains PDF
         response.setHeader('Content-type', 'application/%s' % fileType)