Add Hash wrapper and supporting traits

benches/ledger.rs

@@ -12,7 +12,7 @@ use std::collections::VecDeque;
 
 fn bench_block_to_blobs_to_block(bencher: &mut Bencher) {
     let zero = Hash::default();
-    let one = hash(&zero);
+    let one = hash(&zero.as_ref());
     let keypair = KeyPair::new();
     let tx0 = Transaction::new(&keypair, keypair.pubkey(), 1, one);
     let transactions = vec![tx0; 10];