Bootstrap (#501)

* Renamed fork_choice::process_attestation_from_block

* Processing attestation in fork choice

* Retrieving state from store and checking signature

* Looser check on beacon state validity.

* Cleaned up get_attestation_state

* Expanded fork choice api to provide latest validator message.

* Checking if the an attestation contains a latest message

* Correct process_attestation error handling.

* Copy paste error in comment fixed.

* Tidy ancestor iterators

* Getting attestation slot via helper method

* Refactored attestation creation in test utils

* Revert "Refactored attestation creation in test utils"

This reverts commit 4d277fe4239a7194758b18fb5c00dfe0b8231306.

* Integration tests for free attestation processing

* Implicit conflicts resolved.

* formatting

* Do first pass on Grants code

* Add another attestation processing test

* Tidy attestation processing

* Remove old code fragment

* Add non-compiling half finished changes

* Simplify, fix bugs, add tests for chain iters

* Remove attestation processing from op pool

* Fix bug with fork choice, tidy

* Fix overly restrictive check in fork choice.

* Ensure committee cache is build during attn proc

* Ignore unknown blocks at fork choice

* Various minor fixes

* Make fork choice write lock in to read lock

* Remove unused method

* Tidy comments

* Fix attestation prod. target roots change

* Fix compile error in store iters

* Reject any attestation prior to finalization

* Begin metrics refactor

* Move beacon_chain to new metrics structure.

* Make metrics not panic if already defined

* Use global prometheus gather at rest api

* Unify common metric fns into a crate

* Add heavy metering to block processing

* Remove hypen from prometheus metric name

* Add more beacon chain metrics

* Add beacon chain persistence metric

* Prune op pool on finalization

* Add extra prom beacon chain metrics

* Prefix BeaconChain metrics with "beacon_"

* Add more store metrics

* Add basic metrics to libp2p

* Add metrics to HTTP server

* Remove old `http_server` crate

* Update metrics names to be more like standard

* Fix broken beacon chain metrics, add slot clock metrics

* Add lighthouse_metrics gather fn

* Remove http args

* Fix wrong state given to op pool prune

* Make prom metric names more consistent

* Add more metrics, tidy existing metrics

* Fix store block read metrics

* Tidy attestation metrics

* Fix minor PR comments

* Fix minor PR comments

* Remove duplicated attestation finalization check

* Remove awkward `let` statement

* Add first attempts at HTTP bootstrap

* Add beacon_block methods to rest api

* Fix serde for block.body.grafitti

* Allow travis failures on beta (see desc)

There's a non-backward compatible change in `cargo fmt`. Stable and beta
do not agree.

* Add network routes to API

* Fix rustc warnings

* Add best_slot method

* Add --bootstrap arg to beacon node

* Get bootstrapper working for ENR address

* Store intermediate states during block processing

* Allow bootstrapper to scrape libp2p address

* Update bootstrapper libp2p address finding

* Add comments

* Tidy API to be more consistent with recent decisions

* Address some review comments

* Make BeaconChainTypes Send + Sync + 'static

* Add `/network/listen_port` API endpoint

* Abandon starting the node if libp2p doesn't start

* Update bootstrapper for API changes

* Remove unnecessary trait bounds

eth2/types/src/beacon_block_body.rs

@@ -1,5 +1,5 @@
 use crate::test_utils::TestRandom;
-use crate::utils::graffiti_from_hex_str;
+use crate::utils::{graffiti_from_hex_str, graffiti_to_hex_str};
 use crate::*;
 
 use serde_derive::{Deserialize, Serialize};
@@ -16,7 +16,10 @@ use tree_hash_derive::TreeHash;
 pub struct BeaconBlockBody<T: EthSpec> {
     pub randao_reveal: Signature,
     pub eth1_data: Eth1Data,
-    #[serde(deserialize_with = "graffiti_from_hex_str")]
+    #[serde(
+        serialize_with = "graffiti_to_hex_str",
+        deserialize_with = "graffiti_from_hex_str"
+    )]
     pub graffiti: [u8; 32],
     pub proposer_slashings: VariableList<ProposerSlashing, T::MaxProposerSlashings>,
     pub attester_slashings: VariableList<AttesterSlashing<T>, T::MaxAttesterSlashings>,

eth2/types/src/utils/serde_utils.rs

@@ -46,8 +46,20 @@ where
     Ok(array)
 }
 
-// #[allow(clippy::trivially_copy_pass_by_ref)] // Serde requires the `byte` to be a ref.
-pub fn fork_to_hex_str<S>(bytes: &[u8; 4], serializer: S) -> Result<S::Ok, S::Error>
+pub fn fork_to_hex_str<S>(bytes: &[u8; FORK_BYTES_LEN], serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    let mut hex_string: String = "0x".to_string();
+    hex_string.push_str(&hex::encode(&bytes));
+
+    serializer.serialize_str(&hex_string)
+}
+
+pub fn graffiti_to_hex_str<S>(
+    bytes: &[u8; GRAFFITI_BYTES_LEN],
+    serializer: S,
+) -> Result<S::Ok, S::Error>
 where
     S: Serializer,
 {