Faster BeaconState enc/dec (#671)

* Add state enc/dec benches

* Add example for flamegraph

* Use `PublicKeyBytes` for `Validator`

* Ripple PublicKeyBytes change through codebase

* Add benches, optimizations to store BeaconState

* Store BeaconState in StorageContainer too

* Optimize StorageContainer with std::mem magic

* Fix rest_api tests

eth2/utils/remote_beacon_node/src/lib.rs

@@ -260,7 +260,10 @@ impl<E: EthSpec> Validator<E> {
 
         let bulk_request = BulkValidatorDutiesRequest {
             epoch,
-            pubkeys: validator_pubkeys.to_vec(),
+            pubkeys: validator_pubkeys
+                .iter()
+                .map(|pubkey| pubkey.clone().into())
+                .collect(),
         };
 
         self.url("duties")