Use sidekiq for sending mails
Merge branch 'develop' into use-sidekiq-for-mails

Conflicts:
	config/email_addresses.yml.example
Apply ruby-style guide
Removed the article observer test

Since we're no longer using .deliver here.
ArticleMailer is tested elsewhere anyway?
Merge pull request #982 from BiteKollektiv/use-sidekiq-for-mails

Use sidekiq for sending mails