Move experimental feature to MaxPoolingND.__init__ function.
Move experimental feature to MaxPoolingND.__init__ function.

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