remove unused import statement in keras dir (keras-team#2638)

* remove unused import statement in keras dir

* rewrite import graph statement

Author: nzw0301

keras/datasets/cifar.py

@@ -2,7 +2,6 @@
 from __future__ import absolute_import
 import sys
 from six.moves import cPickle
-from six.moves import range
 
 
 def load_batch(fpath, label_key='labels'):

keras/wrappers/scikit_learn.py

@@ -2,7 +2,6 @@
 import copy
 import inspect
 import types
-import numpy as np
 
 from ..utils.np_utils import to_categorical
 from ..models import Sequential