Code cleanup.

Converted rest of .clone() s on ref pointer to use the macro instead.
Stopped ignoring clippy clone_on_ref_pointer warnings since there shouldn't
be any, anymore.

hammond-downloader/src/downloader.rs

@@ -1,5 +1,3 @@
-#![cfg_attr(feature = "cargo-clippy", allow(clone_on_ref_ptr))]
-
 use reqwest;
 use hyper::header::*;
 use diesel::prelude::*;