Please specify a composer package version.

Recommending people install your code as `dev-master` is not super great as a `composer update` or subsequent deployment might pull in code with different behaviour than what was previously accounted for.

Yes, we _can_ specify `dev-master#{commit-hash}`, but that's a bit kludgey and still requires that `minimum-stability` be set to `dev` in composer.json.

That said, it's a very nice bit of code. Thanks. :D