Permit 'none' as a toolchain
Permit 'none' as a toolchain

In order for the user to install rustup and no toolchain, we must support
the 'none' toolchain which isn't actually a valid name.  As such whitelist
it in the santiy checks.

nodakai/rustup.rs,inejge/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,inejge/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,inejge/rustup.rs,rust-lang/rustup,inejge/rustup.rs,inejge/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,rust-lang/rustup,nodakai/rustup.rs