Add latest commit info to git version

Cargo.lock

@@ -1883,6 +1883,28 @@ version = "0.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bcc8e0c9bce37868955864dbecd2b1ab2bdf967e6f28066d65aaac620444b65c"
 
+[[package]]
+name = "git-version"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94918e83f1e01dedc2e361d00ce9487b14c58c7f40bab148026fa39d42cb41e2"
+dependencies = [
+ "git-version-macro",
+ "proc-macro-hack",
+]
+
+[[package]]
+name = "git-version-macro"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34a97a52fdee1870a34fa6e4b77570cba531b27d1838874fef4429a791a3d657"
+dependencies = [
+ "proc-macro-hack",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "glob"
 version = "0.3.0"
@@ -2744,6 +2766,7 @@ dependencies = [
  "environment",
  "eth2_testnet_config",
  "futures 0.3.5",
+ "git-version",
  "logging",
  "slog",
  "slog-async",

lighthouse/Cargo.toml

@@ -25,6 +25,7 @@ validator_client = { "path" = "../validator_client" }
 account_manager = { "path" = "../account_manager" }
 clap_utils = { path = "../common/clap_utils" }
 eth2_testnet_config = { path = "../common/eth2_testnet_config" }
+git-version = "0.3.4"
 
 [dev-dependencies]
 tempfile = "3.1.0"

lighthouse/src/main.rs

@@ -7,20 +7,23 @@ use clap_utils;
 use env_logger::{Builder, Env};
 use environment::EnvironmentBuilder;
 use eth2_testnet_config::HARDCODED_TESTNET;
+use git_version::git_describe;
 use slog::{crit, info, warn};
 use std::path::PathBuf;
 use std::process::exit;
 use types::EthSpec;
 use validator_client::ProductionValidatorClient;
 
+pub const GIT_LATEST_COMMIT: &str = git_describe!("--always", "--dirty=-modified");
 pub const DEFAULT_DATA_DIR: &str = ".lighthouse";
 pub const CLIENT_CONFIG_FILENAME: &str = "beacon-node.toml";
 pub const ETH2_CONFIG_FILENAME: &str = "eth2-spec.toml";
 
 fn main() {
     // Parse the CLI parameters.
+    let version = format!("{} commit {}", crate_version!(), GIT_LATEST_COMMIT);
     let matches = App::new("Lighthouse")
-        .version(crate_version!())
+        .version(version.as_str())
         .author("Sigma Prime <contact@sigmaprime.io>")
         .setting(clap::AppSettings::ColoredHelp)
         .about(