Move helpers to internal
Move helpers to internal

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