fix building without tls. close #1

src/error.rs

@@ -1,7 +1,11 @@
-use native_tls::Error as TlsError;
-use native_tls::HandshakeError;
 use std::io::Error as IoError;
+
+#[cfg(feature = "tls")]
 use std::net::TcpStream;
+#[cfg(feature = "tls")]
+use native_tls::Error as TlsError;
+#[cfg(feature = "tls")]
+use native_tls::HandshakeError;
 
 /// Errors that are translated to ["synthetic" responses](struct.Response.html#method.synthetic).
 #[derive(Debug)]
@@ -23,8 +27,10 @@ pub enum Error {
     /// Some unspecified `std::io::Error`. Synthetic error `500`.
     Io(IoError),
     /// Some unspecified TLS error. Synthetic error `400`.
+    #[cfg(feature = "tls")]
     Tls(TlsError),
     /// Some unspecified TLS handshake error. Synthetic error `500`.
+    #[cfg(feature = "tls")]
     TlsHandshake(HandshakeError<TcpStream>),
 }
 
@@ -40,7 +46,9 @@ impl Error {
             Error::BadStatus => 500,
             Error::BadHeader => 500,
             Error::Io(_) => 500,
+            #[cfg(feature = "tls")]
             Error::Tls(_) => 400,
+            #[cfg(feature = "tls")]
             Error::TlsHandshake(_) => 500,
         }
     }
@@ -56,7 +64,9 @@ impl Error {
             Error::BadStatus => "Bad Status",
             Error::BadHeader => "Bad Header",
             Error::Io(_) => "Network Error",
+            #[cfg(feature = "tls")]
             Error::Tls(_) => "TLS Error",
+            #[cfg(feature = "tls")]
             Error::TlsHandshake(_) => "TLS Handshake Error",
         }
     }
@@ -72,7 +82,9 @@ impl Error {
             Error::BadStatus => "Bad Status".to_string(),
             Error::BadHeader => "Bad Header".to_string(),
             Error::Io(ioe) => format!("Network Error: {}", ioe),
+            #[cfg(feature = "tls")]
             Error::Tls(tls) => format!("TLS Error: {}", tls),
+            #[cfg(feature = "tls")]
             Error::TlsHandshake(he) => format!("TLS Handshake Error: {}", he),
         }
     }
@@ -84,12 +96,14 @@ impl From<IoError> for Error {
     }
 }
 
+#[cfg(feature = "tls")]
 impl From<TlsError> for Error {
     fn from(err: TlsError) -> Error {
         Error::Tls(err)
     }
 }
 
+#[cfg(feature = "tls")]
 impl From<HandshakeError<TcpStream>> for Error {
     fn from(err: HandshakeError<TcpStream>) -> Error {
         Error::TlsHandshake(err)