Re-generify email confirmation email message, confirm email screen and
its success message because these are also used when user changes their
password. Still think there's a bug here though because confirming the
new email has no effect - the user account's email address was already
changed. Also, need to send confirmation link to old email address,
instead of/as well as new email address, to check ok to change.
Merge pull request #165 from jogwen/email_confirmation_change

Re-generify email confirmation email message, confirm email screen and its success message because these are also used when user changes their password. Still think there's a bug here though because confirming the new email has no effect - the user account's email address was already changed. Also, need to send confirmation link to old email address, not new email address, to check ok to change.