fix colorbar templating for "non-root" colorscales

- propagate template info into colorscale container
- fix marker_colorscale_template baseline which was botched from
  6a47d66

Author: etpinard

src/components/colorscale/defaults.js

@@ -115,6 +115,9 @@ module.exports = function colorScaleDefaults(parentContIn, parentContOut, layout
         if(prefix && inTrace) showScaleDflt = hasColorbar(containerIn);
 
         var showScale = coerce(prefix + 'showscale', showScaleDflt);
-        if(showScale) colorbarDefaults(containerIn, containerOut, layout);
+        if(showScale) {
+            if(prefix && template) containerOut._template = template;
+            colorbarDefaults(containerIn, containerOut, layout);
+        }
     }
 };