allauth: enable ACCOUNT_EMAIL_NOTIFICATIONS option

[stsewd]

What's the problem this feature will solve?

From

ACCOUNT_EMAIL_NOTIFICATIONS (default: False)
When enabled, account related security notifications, such as “Your password was changed”, including information on user agent / IP address from where the change originated, will be emailed.

Describe the solution you'd like

Set that option to True.

[humitos]

Have you tested this? Do we have an example to see how those emails will look like? Do we need to modify our templates?

[stsewd]

Nope, we do probably need to define a template.