* #39101: revert to compatibility fragments

There is an issue in a UI element (ViewPager), which does not get properly populated
when restoring its state. (found using VMs with API=16)
diff --git a/src/org/sflphone/loaders/AccountsLoader.java b/src/org/sflphone/loaders/AccountsLoader.java
index fdb7fd1..81397db 100644
--- a/src/org/sflphone/loaders/AccountsLoader.java
+++ b/src/org/sflphone/loaders/AccountsLoader.java
@@ -34,13 +34,13 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 
+import android.support.v4.content.AsyncTaskLoader;
 import org.sflphone.model.Account;
 import org.sflphone.service.ISipService;
 
 import android.content.Context;
 import android.os.Bundle;
 import android.os.RemoteException;
-import android.content.AsyncTaskLoader;
 import android.util.Log;
 
 public class AccountsLoader extends AsyncTaskLoader<Bundle> {