Removed binding from concat methods

As per deprecation of the binding parameter in rails

lib/google_visualization.rb

@@ -141,7 +141,7 @@ def setup_gap_minder
     def gap_minder_for(collection, options={}, *args, &block)
       gap_minder = GapMinder.new(self, collection, options)
       yield gap_minder
-      concat(gap_minder.render, block.binding)
+      concat(gap_minder.render)
     end
   end
 end