Use wait_for for waiting a process with python 3.5

gns3server/utils/asyncio/__init__.py

@@ -77,6 +77,9 @@ def wait_for_process_termination(process, timeout=10):
     :param timeout: Timeout in seconds
     """
 
+    if sys.version_info >= (3,5):
+        yield from asyncio.wait_for(process.wait(), timeout=timeout)
+    else:
         while timeout > 0:
             if process.returncode is not None:
                 return