title: How to export data in json/csv without pagination
body: <p>I'm using active_admin for one of my projects, and I have some tables with a lot of data (+100,000 records).</p>
  
  <p>Its fine to paginete to browse the data, but when I want to export the data (so I can do custom match in excel), and I try to export in xml, it just export the current records of the page, instead of exporting the total records on the filtering.</p>
  
  <pre><code>module ActiveAdmin
    class ResourceController
      module Collection
        module Pagination
          def max_csv_records
            1_000_000
          end
        end
      end
    end
  end
  </code></pre>
  
  <p>but that won't work for xml/json, any ideas how to solve that?</p>
  
  <p>Thx</p>