Prep-work for a separate payouts view

Blocked out sections in the list_requests template, have a PermissionRequestListing subclass for the new payout view (with empty template), moved table header cell creation into a Jinja macro.
Start an optimized view for doing payouts

The buttons so far will copy the text to the clipboard for quick pasting in-game. It uses ZeroClipboard (a Flash widget) for this, as Javascript does not have access to the system clipboard.
Add button to that payout view for marking requests as paid
Fix bug in trying to add filters to empty request lists
Merge branch 'payout-view'

Closes #3

* payout-view:
  Add button to that payout view for marking requests as paid
  Start an optimized view for doing payouts
  Prep-work for a separate payouts view