Close poll

* Add winner and close buttons
Add ability to close poll

* Owner can close poll
* Invitees cannot close poll
Deny access to editing closed polls
Disable voting for closed polls
Remove reminder buttons when poll is closed
Show modal when selecting winning option
Close poll when winner is chosen
Tighten up tests
modal styled
disabled poll voting state on close
removed close poll button
removed bullhorn
closed status updates
Send notification when winner is chosen
Add winner notification email and tests