Rust bindings for zsign

Note that the ability to zip, unzip, and install has been removed from zsign for simplicity. If you want this functionality you will have to implement it yourself.

let result = zsign_rust::ZSignOptions::new(path_to_app_folder)
    .with_cert_file(path_to_certificate)
    .with_pkey_file(path_to_private_key)
    .with_prov_file(path_to_provisioning_profile)
    .sign();

• A lot of code was borrowed from https://github.com/sfackler/rust-openssl/blob/master/openssl-sys