r11239: Use ${REALM} for the realm in rootdse.ldif

r11239: Use ${REALM} for the realm in rootdse.ldif

Add the kpasswd server to our KDC, implementing the 'original' and
Microsoft versions of the protocol.

This works with the Heimdal kpasswd client, but not with MIT, I think
due to ordering issues.  It may not be worth the pain to have this
code go via GENSEC, as it is very, very tied to krb5.

This gets us one step closer to joins from Apple, Samba3 and other
similar implementations.

Andrew Bartlett
(This used to be commit ab5dbbe10a162286aa6694c7e08de43b48e34cdb)