Move pages from previous years to year-specific URLs

[andrewwoods]

We have some pages from previous years that need to be archived. They should be move to a year-specific URL e.g. /2015/schedule. While some pages are universal - the homepage, code of conduct - new pages that are year specific should begin under it's year. This will help preserve URLS for speakers who link to their talks from their website.

[andrewwoods]

I think I'd like to make controllers that represent the different years, and add methods to handle certain pages. The routes file is currently too cluttered. Create a controller class Year2017 to handle the 2017-specific URL we know we need - sponsors, schedule, speakers.