Fix some unused import warnings.

src/audio_key.rs

@@ -1,4 +1,4 @@
-use byteorder::{BigEndian, ByteOrder, ReadBytesExt, WriteBytesExt};
+use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
 use eventual;
 use std::collections::HashMap;
 use std::io::{Cursor, Read, Write};

src/authentication/mod.rs

@@ -3,7 +3,6 @@ use crypto;
 use crypto::aes;
 use crypto::digest::Digest;
 use crypto::hmac::Hmac;
-use crypto::mac::Mac;
 use crypto::pbkdf2::pbkdf2;
 use crypto::sha1::Sha1;
 use protobuf::ProtobufEnum;