Support scoped packages

[jtojnar]

npm supports so-called scoped packages, whose name has the following form: @somescope/somepackagename. They are used all over the modern NPM ecosystem, most notably by the Babel transpiler. I tried implementing it but unfortunately, it does not seem to be expressible in Servant’s types at the moment.

There is an issue about adding more powerful types to Servant: haskell-servant/servant#962 but I doubt it will be resolved soon.

Would you accept a pull request replacing servant with some less type safe but more flexible library (e.g. scotty)?