Command line tool to query crates.io index.

It contains several query subcommands:
 * Dependencies - list-a-given-crates-dependencies
 * Rust Version - get-the-minimum-rust-version
 * Features - query-features-available
 * Versions - get-versions-published

By default crates-query will always use the latest available, but a specific
version can be specified using the --ver flag.