Get uploader from config instead of app
Get uploader from config instead of app

This removes the need for an app instance in the render-readmes script

steveklabnik/crates.io,rust-lang/crates.io,steveklabnik/crates.io,rust-lang/crates.io,rust-lang/crates.io,steveklabnik/crates.io,steveklabnik/crates.io,rust-lang/crates.io