Postmodern

@grimnight mruby could use some sort of `./configure` script to automate the build process.

We already have a `--no-reinstall` flag which checks for the existence of `$install_dir/bin/ruby`, prints a warning and exits. We could make this behavior the default behavior, and require `--reinstall` or...

Not a lot of interest and I don't have a BSD install handy. Putting this on the backburner for now.

@dysnomian cool! I later realized we have a `fetch` function in `util.sh`. That will probably need to be renamed to avoid shadowing the `fetch` command.

Added one comment. Also, I will probably have to manually merge this into the [0.9.0](https://github.com/postmodern/ruby-install/tree/0.9.0) branch which contains new features for the upcoming release.

What if we allowed passing in the `MRUBY_CONFIG` variable? ``` ruby-install mruby -- MRUBY_CONFIG=/path/to/my/mruby_config.rb ```

Having not used mgem, how does it integrate with mruby? It seems to only be used to generate the `build_config.rb` file?

It sounds like mruby just needs a `./configure` script to allow adding gems/gemboxes.

Submitted mruby/mruby#1711.

Played around with mruby and passing `-- MRUBY_CONFIG=...` _should_ work. Also, we're considering dropping support for mruby since it's more suited for embedding into projects than installing globally. See #168