make billing address optional
Merge remote-tracking branch 'origin/master' into fix-account-save
test update user account details without billing address
test tidy up.
fixed issue with billing address country and postcode reference to country and postcode.
Merge branch 'fix-account-save' of github.com:guardian/frontend into fix-account-save
populate billing address form fields independently of each other
test for: populate billing address form fields independently of each other
Refactoring
Merge remote-tracking branch 'origin/master' into fix-account-save

Conflicts:
	identity/app/form/Mappings.scala
Merge pull request #6773 from guardian/fix-account-save

Fix saving user details without billing address