Rename _ULSIF.py to _ulsif.py

Author: antoinedemathelin

adapt/instance_based/_ULSIF.py renamed to adapt/instance_based/_ulsif.py

@@ -377,4 +377,4 @@ def _fit(self, Xs, Xt, kernel_params,lamb):
         h = h.reshape(-1, 1)
         theta = np.linalg.solve(H+lamb*np.eye(n_centers), h)
         theta[theta<0]=0
-        return theta, centers
+        return theta, centers