Fixes for some comments.
Fixes for some comments.

- Support axis and keepdims of logsumexp
- Do not support axis of softmax
- Use lists instead of tuple when calculate probability.

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