Fix for numpy<1.13
Fix for numpy<1.13

ktnyt/chainer,wkentaro/chainer,hvy/chainer,okuta/chainer,keisuke-umezawa/chainer,chainer/chainer,hvy/chainer,jnishi/chainer,jnishi/chainer,niboshi/chainer,wkentaro/chainer,hvy/chainer,niboshi/chainer,pfnet/chainer,keisuke-umezawa/chainer,chainer/chainer,jnishi/chainer,chainer/chainer,niboshi/chainer,keisuke-umezawa/chainer,wkentaro/chainer,jnishi/chainer,chainer/chainer,hvy/chainer,okuta/chainer,ktnyt/chainer,okuta/chainer,okuta/chainer,tkerola/chainer,wkentaro/chainer,ktnyt/chainer,ktnyt/chainer,niboshi/chainer,keisuke-umezawa/chainer,rezoo/chainer,ronekko/chainer