flash update on remote call

Flash works on the server-side, not on the client side. I *think* (if
someone else knows otherwise, please speak up) what most do is use
replace_html to update the content of the html element that wraps the
flash message. So if you have this:

<div id="notice"><%=h flash[:notice] %></div>

Then you would do this:

render :update do |page|
  page[:notice].replace_html "insert message here"