Fix full_crate()

[joseluis]

Fixes #7

Removed unexistant VersionDownloads.id field

e.g. https://crates.io/api/v1/crates/hyper-native-tls/downloads

This is a working example. Save as src/bin/fix-fullcrate.rs and run cargo run --bin fix-fullcrate to check:

extern crate crates_io_api;
use crates_io_api::SyncClient;

fn main() {
    let client = SyncClient::new();
    let crate_name = "hyper-native-tls";
    let c = client.full_crate(crate_name, false).unwrap();
    println!("name={}", c.name);
}

[theduke]

Thanks.

I pushed your commit to master myself since this PR includes a commit from the other one and I couldn't force push to your branch.

[joseluis]

Right, I missed that. It's all good

[theduke]

I also already released a 0.4.1 version with the fix, FYI.