When a new user registers, we send a verification request to their
email. Currently, if they do not verify their email, we take no further
action. We want to send these users reminders: one after about one day
and one after about 5 days. To do this we will use this new
verification_reminders column.
It will look something like this:
```
SELECT email FROM users
WHERE status = 0
AND (
(verification_reminders = 0 AND created_at < now() - 'INTERVAL 1d')
OR (verification_reminders = 1 AND created_at < now() - 'INTERVAL 5d')
)
```
Change-Id: If0620e08c97e9e337c9563481d665c5bd462693b
