refactor all to async/await (#617)

Co-authored-by: Danny Browning <danny.browning@protectwise.com>
Co-authored-by: Daniel Eades <danieleades@hotmail.com>

tests/timeouts.rs

@@ -1,9 +1,10 @@
 #[macro_use]
 mod support;
 
-use std::io::Read;
 use std::time::Duration;
 
+/// Tests that internal client future cancels when the oneshot channel
+/// is canceled.
 #[test]
 fn timeout_closes_connection() {
     let _ = env_logger::try_init();
@@ -156,7 +157,6 @@ fn test_read_timeout() {
         &"5"
     );
 
-    let mut buf = [0; 1024];
-    let err = res.read(&mut buf).unwrap_err();
+    let err = res.text().unwrap_err();
     assert_eq!(err.to_string(), "timed out");
 }