Currently after each update of any Settings is redirected to the first
tab by default.
As this new tab remote_census_configuation has a lot of fields to fill
in it is a bit uncomfortable to have to go back to the tab after each
update.
- Add hidden field :tag to set current tag value
- After update add tag value to request.referer
- To avoid errors when partial call has not param :tag, add the "define?"
method on hidden_field value.
