Modules support start iou process (not ioucon and iouyap)

gns3server/modules/vm_error.py

@@ -17,4 +17,19 @@
 
 
 class VMError(Exception):
-    pass
+
+    def __init__(self, message, original_exception=None):
+
+        Exception.__init__(self, message)
+        if isinstance(message, Exception):
+            message = str(message)
+        self._message = message
+        self._original_exception = original_exception
+
+    def __repr__(self):
+
+        return self._message
+
+    def __str__(self):
+
+        return self._message