Create poll management front-end

Adds the tables and API calls that we need for poll creators.
Introduce ManageVoteController

Adds a controller to receive Poll Creator requests when viewing and
deleting votes. Currently rejects all calls.
Implement "DELETE /manage/id/vote"

Allows all votes for a given managed session to be reset.
Because we no longer need this functionality in "DELETE /session/id/vote"
we remove it from the latter.
Remove vote from managed session by Id

Implements "DELETE /manage/id/vote/id" to delete a single vote from a
managed session as a poll creator.
Reduce discoverability of sessions

We don't want all sessions to be discoverable, so we remove "GET /session",
as well as removing the ManageID from a "GET /session/id" request.

Otherwise, a regular user could request a session by id, see the manageId
and gain access to the poll creator panel.
GET things

Implements GET /manage/id/vote and GET /manage/id/option
Front end tweaks

- Only center the "Reset Votes" button, not anything else
- Fix ambiguous DELETE call
DELETE /manage/id/option/id
Front-end to add options

Adds the fields to allow poll creators to add new options to a poll
Currently returns 405 when trying to POST, as we haven't hooked the back
up yet.
POST /manage/id/option

Allows creation of new options for a managed session (i.e. by the poll
creator).
Fix for live version

Didn't pick this up with tests due to all the mocking, but we need to
include the Session.Options before we start removing from Session.Options
Merge branch 'feature/fish' into working