Update README.md
added holdays gem to Gemfile.
updated Gemfile source to HTTPS rubygems.org
required Holidays
removed the holidays gem. I just realized I can have a cron run on Mondays so that four-day weekends are caught. The script zeros the inbox when it runs on Sunday so when it runs again Monday, it will notice the new excel file and execute accordingly.
Merge branch 'master' of github.com:datadesk/boxoffice

* 'master' of github.com:datadesk/boxoffice:
  Update README.md
Merge branch 'master' of https://github.com/aboutaaron/boxoffice

* 'master' of https://github.com/aboutaaron/boxoffice:
  Update README.md
  Updated README.md with config.yml instructions