Add validator_node, restructure binaries, gRPC.

This is a massive commit which restructures the workspace, adds a very
basic, untested, validator client and some very basic, non-functioning
gRPC endpoints to the beacon-node.

beacon_node/db/src/stores/mod.rs

@@ -0,0 +1,27 @@
+use super::{ClientDB, DBError};
+
+#[macro_use]
+mod macros;
+mod beacon_block_store;
+mod beacon_state_store;
+mod pow_chain_store;
+mod validator_store;
+
+pub use self::beacon_block_store::{BeaconBlockAtSlotError, BeaconBlockStore};
+pub use self::beacon_state_store::BeaconStateStore;
+pub use self::pow_chain_store::PoWChainStore;
+pub use self::validator_store::{ValidatorStore, ValidatorStoreError};
+
+use super::bls;
+
+pub const BLOCKS_DB_COLUMN: &str = "blocks";
+pub const STATES_DB_COLUMN: &str = "states";
+pub const POW_CHAIN_DB_COLUMN: &str = "powchain";
+pub const VALIDATOR_DB_COLUMN: &str = "validator";
+
+pub const COLUMNS: [&str; 4] = [
+    BLOCKS_DB_COLUMN,
+    STATES_DB_COLUMN,
+    POW_CHAIN_DB_COLUMN,
+    VALIDATOR_DB_COLUMN,
+];