Application version information from git

Creates constant GIT_BUILD_VERSION from git command git describe --tags --always

Add to bulid.rs:

extern crate build_version;
fn main() {
    build_version::write_version_file().expect("Failed to write version.rs file");
}

Add to main.rs:

include!(concat!(env!("OUT_DIR"), "/version.rs"));

build-version

git version for rust applications