include cargo-update

[colin-kiegel]

I suggest to include https://github.com/nabijaczleweli/cargo-update in cargo-extras. I think it's filling an important gap in todays cargo ecosystem. :-)

$ cargo install-update --all
    Updating registry `https://github.com/rust-lang/crates.io-index`

Package       Installed  Latest  Needs update
cargo-expand  v0.1.3     v0.3.7  Yes
// ...

Updating cargo-expand
   // ...
   Replacing /home/colin/.cargo/bin/cargo-expand
$ _