Usability enhancements to the forgot password screen.

* Disable the email field.
* Focus the first password field instead of the email field.
* If no email is stored (user did not come from /signin or /signup), redirect the user to /signin.
* If email address that is stored is not known, redirect to /signup.
* If email address that is stored is known but a primary, redirect to /signin
* When calling User.addressInfo on a primary address, check whether the address is known or not.  Allows us to simplify the forgot page.