Wrap input fields in <form> tag.
New method Alias::unset_email_id ().

The method is used to unset (set to NULL) email_id for all aliases
that are associated with this email_id. This is useful when deleting
email address from the database with which aliases can no longer be
associated.
FIX: undefined variable alias.
New method for API action email_delete.
Style of 'a' element inverted (underline on hover).
Unset email_id for all associated aliases.
Most of the UI elements are functional.

What is working:

- adding new email address
- adding new alias
- deleting email address
- deleting alias
Do not link to GnuGPG wiki page.