rad_getpwnam() now uses strNcopy() and sizeof(), instead

	rad_getpwnam() now uses strNcopy() and sizeof(), instead
	of hard-coded lengths.  The source should be audited in general
	for this sort of problem...

	new functions: rad_get_username() and rad_put_username().
	The intent is to canonicalize the get/set of username hacking.
	e.g. NT_DOMAIN_HACK, JETSTREAM_HACK, Prefix, and Suffix ALL should
	eventually use these functions to get/set the username.