Support multiple year's JSON config

[tunetheweb]

I presume we're going to start on 2020 edition soon. On the most we're set up well for it with folder structures and therefore templating set up for years.

However we have a few things to update including hardcoding 2019 in config.py

  # TODO(rviscomi): Dynamically handle multiple annual configs.
  with open('config/2019.json', 'r') as config_file:
    config_json['2019'] = json.load(config_file)