feat(client): Response.status() now returns a StatusCode

Previously, it would return `&StatusCode`. Returning a reference was
actually bigger than the enum itself, and prevented using `Into` on the
return result directly.

BREAKING CHANGE: If you were explicitly checking the status, such as
  with an equality comparison, you will need to use the value instead of a
  reference.

src/server/request.rs

@@ -37,14 +37,14 @@ impl Request {
 
     /// The version of HTTP for this request.
     #[inline]
-    pub fn version(&self) -> &HttpVersion { &self.version }
+    pub fn version(&self) -> HttpVersion { self.version }
 
     /// The remote socket address of this request
     ///
     /// This is an `Option`, because some underlying transports may not have
     /// a socket address, such as Unix Sockets.
     #[inline]
-    pub fn remote_addr(&self) -> Option<&SocketAddr> { self.remote_addr.as_ref() }
+    pub fn remote_addr(&self) -> Option<SocketAddr> { self.remote_addr }
 
     /// The target path of this Request.
     #[inline]

src/server/response.rs

@@ -26,13 +26,13 @@ impl<B> Response<B> {
 
     /// The status of this response.
     #[inline]
-    pub fn status(&self) -> &StatusCode {
-        &self.head.subject
+    pub fn status(&self) -> StatusCode {
+        self.head.subject
     }
 
     /// The HTTP version of this response.
     #[inline]
-    pub fn version(&self) -> &version::HttpVersion { &self.head.version }
+    pub fn version(&self) -> version::HttpVersion { self.head.version }
 
     /// Get a mutable reference to the Headers.
     #[inline]