Deprecate res.send(obj) json overload

This is an idea for removing the `res.send(obj)` signature and it's other similar signatures that will `JSON.stringify` the value and send it as JSON. In my opinion there is no reason you cannot just type `res.json` instead. Deprecating and removing this overload will mean people do not have to make sure their variable to `res.send` is a string to get HTML output.