Adds Mailchimp integration via their official gem for subscribing to the CoderDojoSF announcements list.
Merge branch 'master' into mailchimp-integration

* master:
  Fix failing tests.
  Fix bug in styles.css
  Precompile styles.css
  Only render image if image_url is present.
  Compile admin assets.
  Do not load app on assets:precompile.

Conflicts:
	app/assets/stylesheets/basscss.css
	app/views/layouts/application.html.erb