Since the poll post handler runs very early in the post creation
process, it's possible to run the handler on an obiviously invalid post.
This change ensures the post's `raw` value is present before
proceeding.
* DEV: Remove spec that we no longer need.
As far as we know, the migration has been successful for a number of
years.
* FIX: Validate number of votes allowed per poll per user.
They can use the remove vote button or select the same option again for
single choice polls.
This commit refactor the plugin to properly organize code and make it
easier to follow.
