Do not load IOU handler on Windows during tests

Fix #159

gns3server/handlers/__init__.py

@@ -31,4 +31,6 @@ from gns3server.handlers.upload_handler import UploadHandler
 from gns3server.handlers.index_handler import IndexHandler
 
 if sys.platform.startswith("linux") or hasattr(sys, "_called_from_test") or os.environ.get("PYTEST_BUILD_DOCUMENTATION") == "1":
-    from gns3server.handlers.api.iou_handler import IOUHandler
+    # IOU runs only on Linux but testsuite work on UNIX platform
+    if not sys.platform.startswith("win"):
+        from gns3server.handlers.api.iou_handler import IOUHandler