Ensure user data is maintained even when registration form fails

Fixes #128

Conflicts:
	app/views/spree/user_registrations/new.html.erb
Merge branch 'source/2-0-stable' into 2-0-stable

# By Ryan Bigg
# Via Ryan Bigg
* source/2-0-stable:
  Ensure user data is maintained even when registration form fails
Used a more specific translation key