Fix clippy warnings (#1385)

## Issue Addressed

NA

## Proposed Changes

Fixes most clippy warnings and ignores the rest of them, see issue #1388.

boot_node/src/lib.rs

@@ -1,6 +1,5 @@
 //! Creates a simple DISCV5 server which can be used to bootstrap an Eth2 network.
 use clap::ArgMatches;
-use slog;
 use slog::{o, Drain, Level, Logger};
 
 use std::convert::TryFrom;