Added icons to notification dropdown

app/src/main/res/menu/main__menu_top__notifications_dropdown.xml

@@ -13,29 +13,36 @@
         <menu>
             <item
                 android:id="@+id/action_notifications_all"
+                android:icon="@drawable/ic_dashboard_black_24dp"
                 android:title="@string/notifications__all" />
 
             <item
                 android:id="@+id/action_notifications_also_commented"
+                android:icon="@drawable/ic_question_answer_black_24dp"
                 android:title="@string/notifications__also_commented" />
 
             <item
                 android:id="@+id/action_notifications_comment_on_post"
+                android:icon="@drawable/ic_comment_black_24dp"
                 android:title="@string/notifications__comment_on_post" />
 
             <item
                 android:id="@+id/action_notifications_liked"
+                android:icon="@drawable/ic_thumb_up_black_24dp"
                 android:title="@string/notifications__liked" />
 
             <item
                 android:id="@+id/action_notifications_mentioned"
+                android:icon="@drawable/ic_person_pin_black_24dp"
                 android:title="@string/notifications__mentioned" />
 
             <item
                 android:id="@+id/action_notifications_reshared"
+                android:icon="@drawable/ic_repeat_black_24dp"
                 android:title="@string/notifications__reshared" />
             <item
                 android:id="@+id/action_notifications_started_sharing"
+                android:icon="@drawable/ic_person_add_black_24dp"
                 android:title="@string/notifications__started_sharing" />
         </menu>
     </item>