Strip out old code

All of these files have been moved to either:

- https://github.com/sigp/lighthouse-beacon
- https://github.com/sigp/lighthouse-validator
- https://github.com/sigp/lighthouse-common

For rationale, see: https://github.com/sigp/lighthouse/issues/197

eth2/utils/bls/src/keypair.rs

@@ -1,16 +0,0 @@
-use super::{PublicKey, SecretKey};
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Keypair {
-    pub sk: SecretKey,
-    pub pk: PublicKey,
-}
-
-impl Keypair {
-    /// Instantiate a Keypair using SecretKey::random().
-    pub fn random() -> Self {
-        let sk = SecretKey::random();
-        let pk = PublicKey::from_secret_key(&sk);
-        Keypair { sk, pk }
-    }
-}