GitLab

Simplify relibc install steps (submodule needs to be updated once relibc commit is in)

See merge request redox-os/redox!1232

Include ramfs in initfs

See merge request redox-os/redox!1233

update bootstrap.sh for macOS brew using steps from The Book

See merge request !1231

Install cargo-config from bootstrap script

See merge request redox-os/redox!1230

Some cookbook entries were failing with an error like this:

```
error: no such subcommand: `config`
```

We can install this subcommand from the bootstrap script, and also
instruct folks in the README to do so manually.