Fixed the File Injection AlertDialog

src/de/tudarmstadt/informatik/hostage/protocol/cifs/PseudoJavaFileDiskDriver.java

@@ -176,7 +176,7 @@ public class PseudoJavaFileDiskDriver extends JavaFileDiskDriver {
     private void displayAlert() {
 
         Context context = null;
-        final Activity activity = (MainActivity)context;
+        final Activity activity = MainActivity.getInstance();
 
         final FragmentManager fragmentManager = activity.getFragmentManager();
         if (fragmentManager != null) {