CLI should accept content from stdin

[victorb]

The js-ipfs should, like the go-ipfs cli, accept input from stdin and add it correctly.

go-ipfs

$ echo "hello" | IPFS_PATH=~/.ipfs-go ipfs add
added QmZULkCELmmk5XNfCgTnCyFgAVxBRBXyDHGGMVoLFLiXEN QmZULkCELmmk5XNfCgTnCyFgAVxBRBXyDHGGMVoLFLiXEN

current js-ipfs

$ echo "hello" | IPFS_PATH=~/.ipfs-js node src/cli/bin.js files add
src/cli/bin.js files add <file>

Options:
  --help           Show help                                           [boolean]
  --recursive, -r                                     [boolean] [default: false]

Not enough non-option arguments: got 0, need at least 1

[daviddias]

Hey @victorbjelkholm mind adding a test case for this showing the failure?

[daviddias]

@gpestana has proposed a fix here: #785

Let's follow up there.