fix client hanging in "download torrent" method when torrent exists.

reason: "downloadComplete" callback will be invoked only when last piece is received and validated. This callback will not be invoked if torrent exists. So it's needed interrupting method in "validation complete" callback if all pieces are valid

ttorrent-client/src/main/java/com/turn/ttorrent/client/SimpleClient.java

@@ -3,6 +3,8 @@
 import java.io.IOException;
 import java.net.InetAddress;
 import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Semaphore;
@@ -55,14 +57,23 @@ public void stop(int timeout, TimeUnit timeUnit) {
   }
 
   public void downloadTorrent(String torrentFile, String downloadDir, InetAddress iPv4Address) throws IOException, InterruptedException {
-    TorrentManager torrentManager = startDownloading(torrentFile, downloadDir, iPv4Address);
+    communicationManager.start(iPv4Address);
     final Semaphore semaphore = new Semaphore(0);
-    torrentManager.addListener(new TorrentListenerWrapper() {
-      @Override
-      public void downloadComplete() {
-        semaphore.release();
-      }
-    });
+    List<TorrentListener> listeners = Collections.<TorrentListener>singletonList(
+            new TorrentListenerWrapper() {
+
+              @Override
+              public void validationComplete(int validpieces, int totalpieces) {
+                if (validpieces == totalpieces) semaphore.release();
+              }
+
+              @Override
+              public void downloadComplete() {
+                semaphore.release();
+              }
+            }
+    );
+    TorrentManager torrentManager = communicationManager.addTorrent(torrentFile, downloadDir, listeners);
     semaphore.acquire();
   }
 
@@ -72,8 +83,8 @@ private TorrentManager startDownloading(String torrentFile, String downloadDir,
   }
 
   public TorrentManager downloadTorrentAsync(String torrentFile,
-                              String downloadDir,
-                              InetAddress iPv4Address) throws IOException {
+                                             String downloadDir,
+                                             InetAddress iPv4Address) throws IOException {
     return startDownloading(torrentFile, downloadDir, iPv4Address);
   }
 }