Remove invalid brew option from Travis CI
Remove invalid brew option from Travis CI

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