Support -V/--version on all CLI apps

All CLI apps that use clap (in other words, except for bench-streamer)
can use crate_version! to take the version from Cargo.toml.

This change addresses #700.

src/bin/fullnode-config.rs

@@ -1,3 +1,4 @@
+#[macro_use]
 extern crate clap;
 extern crate dirs;
 extern crate serde_json;
@@ -13,6 +14,7 @@ use std::net::SocketAddr;
 
 fn main() {
     let matches = App::new("fullnode-config")
+        .version(crate_version!())
         .arg(
             Arg::with_name("local")
                 .short("l")