parsemail: Always update Person.email

parsemail: Always update Person.email

Patches applied using pwclient will always use the first name that has
been seen for a particular email address. While this is usually fine,
ot actually causes issues for people changing name without changing
email addresses or people changing the capitalization of their name.
Resolve this by always updating the Person object when we receive a
new submission or comment.

Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>
Reviewed-by: Andy Doan <andy.doan@linaro.org>
Closes: #24