Clean up DeviceInternals and some cosmetics
Clean up DeviceInternals and some cosmetics

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