Resolve "Impl Serialize trait for Idty, Membership, Cert and Revoc docs and PublicKey"

Closes #55 (closed)

crypto/keys/ed25519.rs

@@ -19,6 +19,8 @@
 //!
 //! [`KeyPairGenerator`]: struct.KeyPairGenerator.html
 
+extern crate serde;
+
 use std::collections::hash_map::DefaultHasher;
 use std::fmt::Debug;
 use std::fmt::Display;
@@ -26,6 +28,7 @@ use std::fmt::Error;
 use std::fmt::Formatter;
 use std::hash::{Hash, Hasher};
 
+use self::serde::ser::{Serialize, Serializer};
 use base58::{FromBase58, FromBase58Error, ToBase58};
 use base64;
 use base64::DecodeError;
@@ -123,6 +126,15 @@ impl Debug for PublicKey {
     }
 }
 
+impl Serialize for PublicKey {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&format!("{}", self))
+    }
+}
+
 impl super::PublicKey for PublicKey {
     type Signature = Signature;