add Codecov.io configuration
add Codecov.io configuration

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