@Override
    public AuthenticationHandler create() {
        return new Handler();
    }
Implements the SMTP AUTH LOGIN mechanism.<br>
You are only required to plug your UsernamePasswordValidator implementation
for username and password validation to take effect.
<p>
LOGIN is an obsolete authentication method which has no formal specification.
There is an expired IETF draft for informational purposes. A Microsoft
document can also be found, which intends to specify the LOGIN mechanism. The
latter is not entirely compatible, neither with the IETF draft nor with RFC
4954 (SMTP Service Extension for Authentication). However this implementation
is likely usable with clients following any of the two documents.

@see <a href="http://tools.ietf.org/html/draft-murchison-sasl-login-00">The
LOGIN SASL Mechanism</a>
@see <a href=
"http://download.microsoft.com/download/5/d/d/5dd33fdf-91f5-496d-9884-0a0b0ee698bb/%5BMS-XLOGIN%5D.pdf">[MS-XLOGIN]</a>
src/main/java/de/gessnerfl/fakesmtp/smtp/auth/LoginAuthenticationHandlerFactory.java