Fix Host header is broken on virtual host, close AsyncHttpClient#907

Author: slandelle

src/main/java/com/ning/http/client/providers/netty/request/NettyRequestFactory.java

@@ -83,9 +83,14 @@ else if (proxyServer != null && !(useProxyConnect(uri) && config.isUseRelativeUR
     }
 
     private String hostHeader(Request request, Uri uri) {
-        String host = request.getVirtualHost() != null ? request.getVirtualHost() : uri.getHost();
-        int port = uri.getPort();
-        return port == -1 || port == getSchemeDefaultPort(uri.getScheme()) ? host : host + ":" + port;
+        String virtualHost = request.getVirtualHost();
+        if (virtualHost != null)
+            return virtualHost;
+        else {
+            String host = uri.getHost();
+            int port = uri.getPort();
+            return port == -1 || port == getSchemeDefaultPort(uri.getScheme()) ? host : host + ":" + port;
+        }
     }
 
     public String firstRequestOnlyAuthorizationHeader(Request request, Uri uri, ProxyServer proxyServer, Realm realm) throws IOException {