Enable eth1 flag when eth1-endpoint is suppilied (#941)

beacon_node/src/config.rs

@@ -216,6 +216,7 @@ pub fn get_configs<E: EthSpec>(
 
     // Defines the URL to reach the eth1 node.
     if let Some(val) = cli_args.value_of("eth1-endpoint") {
+        client_config.sync_eth1_chain = true;
         client_config.eth1.endpoint = val.to_string();
     }