title: How to export all rows as CSV in ModelAdmin (SilverStripe 3.1)?
body: <p>Apparently the <code>GridFieldExportButton</code> only exports the currently visible data-set (paginated). Is there a way to make it export all the rows from a model?</p>
  
  <p>Or alternatively: Is there a way to show all rows (eg. bypass pagination), so that the user can perform an export after showing all the rows? I don't want to show all rows all the time (which would probably be possible by setting <code>ModelAdmin::set_page_length(&lt;ridiculouslyHighNumber&gt;);</code>) but only on demand.</p>