add autodesign routes

Signed-off-by: manuedelf <59697943+edelfour@users.noreply.github.com>

gnpy/api/exception/path_computation_error.py

@@ -0,0 +1,14 @@
+# coding: utf-8
+
+
+class PathComputationError(Exception):
+    """ Exception raise for path computation error error
+    Attributes:
+        message -- explanation of the error
+    """
+
+    def __init__(self, message):
+        self.message = message
+
+    def __str__(self):
+        return self.message