Clear any notifications on daemon start

Ongoing call notifications are persistent in the status bar.
These notifications are not cleared if something goes wrong in the app,
and user can't delete them.
This patch makes sure that when the daemon starts all previous
notifications are cleared.

Change-Id: Ia568ae9136cab113d09285effbebef514f1b2d5c
Reviewed-by: Adrien Béraud <adrien.beraud@savoirfairelinux.com>

ring-android/app/src/main/java/cx/ring/service/LocalService.java

@@ -22,7 +22,6 @@ package cx.ring.service;
 import android.Manifest;
 import android.app.PendingIntent;
 import android.app.Service;
-import android.content.AsyncTaskLoader;
 import android.content.BroadcastReceiver;
 import android.content.ComponentName;
 import android.content.ContentResolver;
@@ -45,7 +44,6 @@ import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Binder;
 import android.os.IBinder;
-import android.os.OperationCanceledException;
 import android.os.RemoteException;
 import android.preference.PreferenceManager;
 import android.provider.ContactsContract;
@@ -321,6 +319,8 @@ public class LocalService extends Service implements SharedPreferences.OnSharedP
         mediaManager = new MediaManager(this);
 
         notificationManager = NotificationManagerCompat.from(this);
+        // Clear any notifications from a previous app instance
+        notificationManager.cancelAll();
 
         final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
         final int cacheSize = maxMemory / 8;