Merge pull request #2 from paulgrock/vote-sub-docs

Vote sub docs
refactored payouts calculator

Since all arguments needed to calculate a payout are based on poll
attributes, we just pass the entire poll object as an arg.
Merge pull request #3 from yobennett/refactor-payouts-calculator

refactored payouts calculator
votes for a poll are their own separate collection.

each vote in the collection belongs to a particular poll referenced by poll._id
this should allow calculating things like rollling votes and accuracy better.
It also decouples polls and votes which is more flexible.