add torchani src code

tests/test_ase.py

@@ -3,10 +3,10 @@ from ase.md.langevin import Langevin
 from ase.md.nptberendsen import NPTBerendsen
 from ase import units
 from ase.io import read
-from ase.calculators.test import numeric_force
+from ase.calculators.fd import _numeric_force as numeric_force
 from torchani.testing import TestCase
 import numpy as np
-import torch
+import torch 
 import torchani
 import unittest
 import os