also translate mail subjects
Merge branch 'rails3' into foodcoop

Conflicts:
	config/locales/de/de.mailer.yml
	config/locales/en/en.mailer.yml
also translate mailer changes for selfsignup
Merge branch 'rails3-selfsignup' into foodcoop

Conflicts:
	config/locales/en/en.mailer.yml