Expose Codec via an unstable flag (#49)

Exposes `Codec` using an unstable flag. This is useful for testing.

src/frame/reset.rs

@@ -2,7 +2,7 @@ use frame::{self, Head, Error, Kind, StreamId, Reason};
 
 use bytes::{BufMut, BigEndian};
 
-#[derive(Debug)]
+#[derive(Debug, Eq, PartialEq)]
 pub struct Reset {
     stream_id: StreamId,
     error_code: u32,