change email footer text - fixes #495
remove default_transport - fixes #483
change email texts - fixes #474 and fixes new requirements for #495
improve email footer display
Merge branch 'release' into develop

Conflicts:
	app/models/article/attributes.rb
	config/locales/de.yml
	config/locales/gems/enumerize/de.yml
	spec/features/articles_spec.rb
	spec/features/mailer_spec.rb