Support stride and pad in backward
Support stride and pad in backward

keisuke-umezawa/chainer,jnishi/chainer,ysekky/chainer,niboshi/chainer,pfnet/chainer,benob/chainer,kashif/chainer,okuta/chainer,wkentaro/chainer,okuta/chainer,chainer/chainer,cemoody/chainer,ronekko/chainer,niboshi/chainer,wkentaro/chainer,jnishi/chainer,rezoo/chainer,wkentaro/chainer,kikusu/chainer,okuta/chainer,keisuke-umezawa/chainer,AlpacaDB/chainer,kiyukuta/chainer,cupy/cupy,okuta/chainer,niboshi/chainer,cupy/cupy,ktnyt/chainer,aonotas/chainer,keisuke-umezawa/chainer,delta2323/chainer,AlpacaDB/chainer,hvy/chainer,chainer/chainer,jnishi/chainer,jnishi/chainer,chainer/chainer,ktnyt/chainer,kikusu/chainer,chainer/chainer,hvy/chainer,keisuke-umezawa/chainer,tkerola/chainer,cupy/cupy,wkentaro/chainer,cupy/cupy,ktnyt/chainer,hvy/chainer,anaruse/chainer,niboshi/chainer,hvy/chainer,benob/chainer,ktnyt/chainer