Bumped the expiry date of the alpha build to 31 July 2013.

briar-android/src/net/sf/briar/android/HomeScreenActivity.java

@@ -62,8 +62,8 @@ import com.google.inject.Inject;
 
 public class HomeScreenActivity extends RoboActivity {
 
-	// This build expires on 15 July 2013
-	private static final long EXPIRY_DATE = 1373846400 * 1000L;
+	// This build expires on 31 July 2013
+	private static final long EXPIRY_DATE = 1375228800 * 1000L;
 
 	private static final Logger LOG =
 			Logger.getLogger(HomeScreenActivity.class.getName());