email address should be editable

[jshslsky]

Users should be able to edit their email addresses.

[jshslsky]

The idea with this issue is that users may want to receive email at a different address than they use for logging in. There is complexity with this issue because what happens when a Shib user changes their email address. We could disallow this feature for those users, but they are the majority of our users. Marking this as low priority for now.