Add logging to the legacy controller

To figure out what app is calling this

Author: jcoyne

app/controllers/legacy_image_service_controller.rb

@@ -8,6 +8,7 @@ class LegacyImageServiceController < ApplicationController
   ##
   # Redirect legacy image requests to their IIIF equivalents
   def show
+    logger.info("  HTTP Referer: #{request.referer[0..100]}")
     redirect_to iiif_path(iiif_options)
   end