Add optional native-tls support, clear up warnings for flag configurations

src/lib.rs

@@ -7,6 +7,7 @@
 //! * Obvious API
 //!
 //! ```
+//! # #[cfg(feature = "json")] {
 //! // requires feature: `ureq = { version = "*", features = ["json"] }`
 //! # #[cfg(feature = "json")] {
 //! use ureq::json;
@@ -195,7 +196,7 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "tls")]
+    #[cfg(any(feature = "tls", feature = "native-tls"))]
     fn connect_https_google() {
         let resp = get("https://www.google.com/").call();
         assert_eq!(
@@ -206,7 +207,7 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "tls")]
+    #[cfg(any(feature = "tls", feature = "native-tls"))]
     fn connect_https_invalid_name() {
         let resp = get("https://example.com{REQUEST_URI}/").call();
         assert_eq!(400, resp.status());