fixing RH OS detection

fixes issue https://github.com/ghoneycutt/puppet-module-inittab/issues/68: Using operatingsystemmajrelease breaks on RedHat 6.5.
Also true when LSB packages are installed:

<pre>
[root@test ~]# rpm -qa | grep lsb
redhat-lsb-printing-4.0-7.el6.x86_64
redhat-lsb-4.0-7.el6.x86_64
redhat-lsb-core-4.0-7.el6.x86_64
redhat-lsb-compat-4.0-7.el6.x86_64
redhat-lsb-graphics-4.0-7.el6.x86_64

[root@test ~]# facter operatingsystemmajrelease
[root@test ~]# facter operatingsystemrelease
6.5
</pre>