Add the test for public AsContiguous
Add the test for public AsContiguous

along with the test for AsContiguous with a scalar.

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