Acquire Wi-Fi lock before downloading. Should fix issue #110 and #243

- Adds the WAKE_LOCK permission

AndroidManifest.xml

@@ -6,6 +6,7 @@
 
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
 
     <uses-sdk
         android:minSdkVersion="10"

src/de/danoeh/antennapod/service/download/Downloader.java

@@ -1,5 +1,8 @@
 package de.danoeh.antennapod.service.download;
 
+import android.content.Context;
+import android.net.wifi.WifiManager;
+import de.danoeh.antennapod.PodcastApp;
 import de.danoeh.antennapod.R;
 
 import java.util.concurrent.Callable;
@@ -26,7 +29,19 @@ public abstract class Downloader implements Callable<Downloader> {
 	protected abstract void download();
 
 	public final Downloader call() {
+        WifiManager wifiManager = (WifiManager) PodcastApp.getInstance().getSystemService(Context.WIFI_SERVICE);
+        WifiManager.WifiLock wifiLock = null;
+        if (wifiManager != null) {
+            wifiLock = wifiManager.createWifiLock(TAG);
+            wifiLock.acquire();
+        }
+
 		download();
+
+        if (wifiLock != null) {
+            wifiLock.release();
+        }
+
 		if (result == null) {
 			throw new IllegalStateException(
 					"Downloader hasn't created DownloadStatus object");