Optionally debounce updates

[julianrubisch]

This adds a debounce option to updates_for (or, the <updates-for> element)

so you can do

<%= updates_for(user, debounce: 100) do %>
...
<% end %>

in case you are updating a lot of records and thus are requesting a lot of fetches. If you omit the option, it just works as normal