Bug #1446: Forgotten password helper only sends to default email address

Just say you have a user who:

1. Signs up with address john@example.com
2. Adds address john@example.net when his company loses control of the example.com domain
3. Forgets his password, and enters "john@example.net" into the forgotten passphrase helper

The helper will display a flash saying that an email was sent to "john@example.net".

This is not true: the email was in fact sent to the default email address for the account ("john@example.com").

So we have to make a couple of changes here:

1. Most urgently, we have to ensure that the "to" address for the forgotten password message is the one that the user enters, regardless of the default email address for the account
2. Secondly, less importantly, we have to make it more obvious how to set new default addresses (perhaps automatically offer to make new addresses the default at the time they are added? or perhaps when confirmed? or perhaps just provide a checkbox on the "add address" form allowing the user to indicate that this should become the new default)