Add `.recursive` on config::File

[mehcode]

Allow to control upwards recursion when searching for configuration files. The only real question is if the upwards recursion should be default true or false.

// ./config/default.toml OR ../config/default.toml 
// OR ../../config/default.toml (etc., whatever ends up matching)
File::with_name("config/default.toml").recursive(true)

[tmccombs]

To me, I would expect "recursive" to search down the file hierarchy recursively not up. That name seems odd to me.

[mehcode]

I agree. I can't think of a good name unless I make it super long. Ideas are welcome.

[tmccombs]

search_parents?

[mehcode]

Hmm. I could just leave this out and tell people to use something like the findup crate.

extern crate config;
extern crate findup;

fn main() {
  let settings = config::Config::default()
    .merge(config::File::from(findup::findup("config/default.toml"))
    .unwrap();
}

[mehcode]

Closing because the above solution is simple enough if that's what you want.