OC-3311: Update background color of image preview to black

res/layout/preview_image_fragment.xml

@@ -26,13 +26,12 @@
     android:background="@color/background_color" 
     android:gravity="center_horizontal"
 -->
-
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/top"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
-    android:background="@color/background_color"
+    android:background="#000000"
     tools:context=".ui.fragment.PreviewImageFragment" >
 
     <ProgressBar