chore(lib): add deny(warnings) back that was mistakenly removed

Author: seanmonstar

src/lib.rs

@@ -1,6 +1,6 @@
 #![doc(html_root_url = "https://docs.rs/hyper/0.11.1")]
 #![deny(missing_docs)]
-//#![deny(warnings)]
+#![deny(warnings)]
 #![deny(missing_debug_implementations)]
 #![cfg_attr(all(test, feature = "nightly"), feature(test))]