Another pass at the patch.

Sorry about having them all together,  tried to break it apart but it 
would take forever.

Moved can_kerberos to chkpwd_macros so all auth_chkpwd functions
automatically get can_kerberos and can_ypbind.   Might add a boolean for
can_kerberos or maybe just can_network_auth and eliminate can_network
from auth_chkpwd.

Removed the rest of single_userdomain

Colins patch of dbus

Cleanup of nfs_home_dir to boolean

Dan