Add a versus mode

[cletusc]

15 will add sub/follow options. One of the streamers that @Muddr talked to suggested we do a "versus" mode, where, once the option is checked, have it automatically track two polls, one for sub/follow, and one for non-sub/follow and show both charts on the same page. Basically, to compete with eachother. Users would need to be logged in to vote in either, but which poll their vote counts towards would be automatic.

This might require a decent change in model structure to accommodate this, so I am considering this low priority until the rest of the site is functioning.

[Muddr]

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