Restore DLNA support class (reverts part of d6264630)

The classes from org.fourthline.cling.transport.impl.apache are actually
needed to make Cling (the UPnP/DLNA) library work on Apache Tomcat, as
explained in the documentation[0]:

> However, if you are trying to use Cling Core in a runtime container such as Tomcat, JBoss AS, or
> Glassfish, you might run into an error on startup. [...] If your container is already using the
> HTTPURLConnection, you have to switch Cling to an alternative HTTP client. See Configuring network
> transports for other available options and how to change various network-related settings.

[0] http://4thline.org/projects/cling/core/manual/cling-core-manual.xhtml#section.BasicAPI.UpnpService.Configuration

airsonic-main/src/main/java/org/airsonic/player/service/UPnPService.java

@@ -19,10 +19,10 @@
  */
 package org.airsonic.player.service;
 
+import org.airsonic.player.service.upnp.ApacheUpnpServiceConfiguration;
 import org.airsonic.player.service.upnp.CustomContentDirectory;
 import org.airsonic.player.service.upnp.MSMediaReceiverRegistrarService;
 import org.airsonic.player.util.FileUtil;
-import org.fourthline.cling.DefaultUpnpServiceConfiguration;
 import org.fourthline.cling.UpnpService;
 import org.fourthline.cling.UpnpServiceImpl;
 import org.fourthline.cling.binding.annotations.AnnotationLocalServiceBinder;
@@ -122,7 +122,7 @@ public class UPnPService {
     }
 
     private synchronized void createService() {
-        upnpService = new UpnpServiceImpl(new DefaultUpnpServiceConfiguration(SettingsService.getDefaultUPnPPort()));
+        upnpService = new UpnpServiceImpl(new ApacheUpnpServiceConfiguration());
 
         // Asynch search for other devices (most importantly UPnP-enabled routers for port-mapping)
         upnpService.getControlPoint().search();

airsonic-main/src/main/java/org/airsonic/player/service/upnp/ApacheUpnpServiceConfiguration.java

@@ -0,0 +1,51 @@
+/*
+ This file is part of Airsonic.
+
+ Airsonic is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Airsonic is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with Airsonic.  If not, see <http://www.gnu.org/licenses/>.
+
+ Copyright 2016 (C) Airsonic Authors
+ Based upon Subsonic, Copyright 2013 (C) Sindre Mehus
+ */
+package org.airsonic.player.service.upnp;
+
+import org.fourthline.cling.DefaultUpnpServiceConfiguration;
+import org.fourthline.cling.transport.impl.apache.StreamClientConfigurationImpl;
+import org.fourthline.cling.transport.impl.apache.StreamClientImpl;
+import org.fourthline.cling.transport.impl.apache.StreamServerConfigurationImpl;
+import org.fourthline.cling.transport.impl.apache.StreamServerImpl;
+import org.fourthline.cling.transport.spi.NetworkAddressFactory;
+import org.fourthline.cling.transport.spi.StreamClient;
+import org.fourthline.cling.transport.spi.StreamServer;
+
+import java.util.concurrent.Executors;
+
+/**
+ * UPnP configuration which uses Apache HttpComponents.  Needed to make UPnP work
+ * when deploying on Tomcat.
+ *
+ * @author Sindre Mehus
+ * @version $Id$
+ */
+public class ApacheUpnpServiceConfiguration extends DefaultUpnpServiceConfiguration {
+
+    @Override
+    public StreamClient createStreamClient() {
+        return new StreamClientImpl(new StreamClientConfigurationImpl(Executors.newCachedThreadPool()));
+    }
+
+    @Override
+    public StreamServer createStreamServer(NetworkAddressFactory networkAddressFactory) {
+        return new StreamServerImpl(new StreamServerConfigurationImpl(networkAddressFactory.getStreamListenPort()));
+    }
+}