Fixes vote limiting by ID

Uses the `X-Forwarded-For` header to determine users' IP addresses, instead of naively using Heroku's internal IPs, so duplicate votes are now correctly prevented.

Fixes a bug that would cause a title to be un-votable by all users once a user who has voted for it reloads the page. (`var newTitle = title;` was creating a reference, but we needed a copy of the original title object.)

Makes some minor style improvements.

Yup. https://github.com/cliss/accidentalbot/commit/5c2e317e5b966ef4e619628332d3a04a0b21b267#diff-b39b1cc27d856a8bad2d0a327e4b3fe8R23