Initial beacon node setup.

- Add network crate.
- Add sync crate.
- Add version crate.
- Add lighthouse configuration.
- Add network configuration.

beacon_node/db/src/lib.rs

@@ -12,3 +12,10 @@ use self::stores::COLUMNS;
 pub use self::disk_db::DiskDB;
 pub use self::memory_db::MemoryDB;
 pub use self::traits::{ClientDB, DBError, DBValue};
+
+/// Currently available database options
+#[derive(Debug, Clone)]
+pub enum DBType {
+    Memory,
+    RocksDB,
+}

beacon_node/db/src/stores/beacon_block_store.rs

@@ -38,7 +38,7 @@ impl<T: ClientDB> BeaconBlockStore<T> {
         }
     }
 
-    /// Retuns an object implementing `BeaconBlockReader`, or `None` (if hash not known).
+    /// Returns an object implementing `BeaconBlockReader`, or `None` (if hash not known).
     ///
     /// Note: Presently, this function fully deserializes a `BeaconBlock` and returns that. In the
     /// future, it would be ideal to return an object capable of reading directly from serialized