Add "bin" entry to package json

[aisamu]

Hi!

There's a commit (a229795) that mentions this was removed because it was unused, but might not be completely the case.

When you run npm tools on a per-project basis, the first spot to look is under node_modules/.bin. This is the spot where npm symlinks all the executables present on the various node_modules.

kinesis-tail's node module appears to have an empty /bin, but a populated /cmd. If I interpreted the documentation correctly, that means our package.json would need to contain:

"bin": "./cmd/kinesis-tail"

But I've just realized that there's not even a package.json anymore 😢

Thanks for the awesome tool!