Fix incorrect Fresco initialization. (commons-app#1895)

Fresco only needs to be initialized once, in the Application class.
Initializing it again can lead to undefined behavior, including crashes.

Author: dbrant

app/src/main/java/fr/free/nrw/commons/quiz/QuizActivity.java

@@ -13,7 +13,6 @@
 import android.widget.RadioButton;
 import android.widget.TextView;
 
-import com.facebook.drawee.backends.pipeline.Fresco;
 import com.facebook.drawee.drawable.ProgressBarDrawable;
 import com.facebook.drawee.generic.GenericDraweeHierarchy;
 import com.facebook.drawee.generic.GenericDraweeHierarchyBuilder;
@@ -45,7 +44,6 @@ public class QuizActivity extends AppCompatActivity {
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_quiz);
-        Fresco.initialize(this);
 
         quizController.initialize(this);
         ButterKnife.bind(this);