Binds functions on request instead of req

Hi! 

I'm trying to retrieve certain fields that are only available on the koa ctx.request object in the `passport.authenticate` function of my Strategy. The problem is that the object passed by the middleware is the raw node request object instead of the koa request object 

     middleware(ctx.req, res, done) 

https://github.com/rkusa/koa-passport/blob/master/lib/framework/koa.js#L111

Is there a way to work around that?

One way would be to bind everything on the ctx.request object instead of ctx.req. But it would change what users are used to... So like instead of `ctx.req.user` to retrieve user it would be `ctx.request.user` and so on.

This way it's way easier to interact with special function of request like host/protocol/charset/etc.