Add argument to control interval for seq2seq example
Add argument to control interval for seq2seq example

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