[FIX] theme_default: full width in mobile

When a theme is customized to be 'boxed', the website is not full width
in mobile, and there is an horizontal scrolling.

To fix this issue, we removed only set the width of the "wrapwrap" div
to 85% when the screen is bigger than a phone.

addons/theme_default/static/src/less/option_layout_boxed.less

@@ -1,4 +1,6 @@
 #wrapwrap {
-    width: 85%;
-    margin: 0 auto;
-}
+    @media (min-width: @screen-sm-min){
+        width: 85%;
+        margin: 0 auto;
+    }
+}