First working version of protocol handshake.

Key exchange and authentication is functional.
Protocol definition has been moved to separate crate to speed up build time.
Various cleanups. Take login info from command line, rather than hardcoded.

protocol/build.rs

@@ -0,0 +1,45 @@
+use std::env;
+use std::process::{Command, Stdio};
+use std::path::{Path,PathBuf};
+
+#[derive(Debug)]
+enum ProtobufError {
+    IoError(::std::io::Error),
+    Other
+}
+
+impl std::convert::From<::std::io::Error> for ProtobufError {
+    fn from(e: ::std::io::Error) -> ProtobufError {
+        ProtobufError::IoError(e)
+    }
+}
+
+fn compile(prefix : &Path, files : &[&Path]) -> Result<(),ProtobufError>{
+    let mut c = Command::new("protoc");
+    c.arg("--rust_out").arg(env::var("OUT_DIR").unwrap())
+        .arg("--proto_path").arg(prefix.to_str().unwrap());
+
+    for f in files.iter() {
+        c.arg(f.to_str().unwrap());
+    }
+
+    //c.stdout(Stdio::inherit());
+    c.stderr(Stdio::inherit());
+
+    let mut p = try!(c.spawn());
+    let r = try!(p.wait());
+    return match r.success() {
+        true => Ok(()),
+        false => Err(ProtobufError::Other),
+    };
+}
+
+fn main() {
+    let root = PathBuf::from(&env::var("CARGO_MANIFEST_DIR").unwrap());
+    let proto = root.join("proto");
+    compile(&proto, &[
+            &proto.join("keyexchange.proto"),
+            &proto.join("authentication.proto")
+    ]).unwrap();
+}
+