Merge branch 'master' into v0.5.0-state-transition-tests

Signed-off-by: Kirk Baird <baird.k@outlook.com>

eth2/utils/bls/src/keypair.rs

@@ -14,4 +14,8 @@ impl Keypair {
         let pk = PublicKey::from_secret_key(&sk);
         Keypair { sk, pk }
     }
+
+    pub fn identifier(&self) -> String {
+        self.pk.concatenated_hex_id()
+    }
 }