htpassword file incorrect on Redhat

Right now, htpasswdfile on Redhat defaults to /etc/nagios/htpasswd.users.  Instead, it should be /etc/nagios/passwd.

```
[root@puppet-dev httpd]# rpm -qf /etc/nagios/passwd 
nagios-3.5.1-1.el6.x86_64
[root@puppet-dev httpd]# rpm -q --filesbypkg nagios | grep passwd
nagios                    /etc/nagios/passwd
```