Simple fetch and unroll .tar.gz archives

Simple functions intended to use in Rust build.rs scripts for tasks which related to fetching from HTTP and unrolling .tar.gz archives with precompiled binaries and etc.

Usage example

```rust use fetch_unroll::Fetch;

let packurl = format!( concat!("{base}/{user}/{repo}/releases/download/", "{package}-{version}/{package}{target}_{profile}.tar.gz"), base = "https://github.com", user = "katyo", repo = "aubio-rs", package = "libaubio", version = "0.5.0-alpha", target = "armv7-linux-androideabi", profile = "debug", );

let destdir = "target/testdownload";

// Fetching and unrolling archive Fetch::from(packurl) .unroll().stripcomponents(1).to(dest_dir) .unwrap(); ```