upgrade dependencies

Rust 1.15+ now supports serde codegen on stable without the build.rs.
Update to serde 0.9 and uuid crate 0.4 to match.

src/main.rs

@@ -51,6 +51,7 @@ extern crate openssl;
 extern crate regex;
 extern crate rustc_serialize;
 extern crate serde;
+#[macro_use] extern crate serde_derive;
 extern crate serde_json;
 extern crate slog;
 extern crate slog_envlogger;
@@ -68,6 +69,7 @@ mod db;
 mod dir;
 mod error;
 mod h264;
+mod json;
 mod mmapfile;
 mod mp4;
 mod pieces;