Product gallery metabox should use thumbnails

Not full size images.

admin/post-types/writepanels/writepanel-product_images.php

@@ -37,7 +37,7 @@ function woocommerce_product_images_box() {
 				if ( $attachments )
 					foreach ( $attachments as $attachment_id ) {
 						echo '<li class="image" data-attachment_id="' . $attachment_id . '">
-							' . wp_get_attachment_image( $attachment_id, 'full' ) . '
+							' . wp_get_attachment_image( $attachment_id, 'thumbnail' ) . '
 							<ul class="actions">
 								<li><a href="#" class="delete" title="' . __( 'Delete image', 'woocommerce' ) . '">' . __( 'Delete', 'woocommerce' ) . '</a></li>
 							</ul>
@@ -161,4 +161,4 @@ function woocommerce_product_images_box() {
 		});
 	</script>
 	<?php
-}
+}