avoid double import of numpy

SimPEG/Tests.py

@@ -4,7 +4,6 @@ from SimPEG.Utils import mkvc, sdiag, diagEst
 from SimPEG import Utils
 from SimPEG.Mesh import TensorMesh, CurvilinearMesh, CylMesh
 from SimPEG.Mesh.TreeMesh import TreeMesh as Tree
-import numpy as np
 import scipy.sparse as sp
 import unittest
 import inspect