Add Atom feed.

Once upon a time I realised I didn’t see any of Lindsey’s blog posts in my feed reader. Almost immediately I attempted to rectify the situation but was told in no uncertain terms that no feed could be found! “Surely this could not be. I must rectify this!”, I thought. So, here we are.

Your blog does not currently track when posts are updated (I have an `updated` entry in my YAML front matter) so any changes you make to existing posts may not show up in people’s feed readers.

Additionally, since only dates are stored, the timestamps are outputted at midnight in the server’s time zone. I can’t remember if Heroku uses US/East or UTC. IMO, this is not a big deal (my blog has the same issue). You could offset the timestamps in the feed if you have a more suitable time of day to report.