RH/CentOS release version comparison fix

New CentOS 7 contains version information consisted of three components

    # facter | grep -i 7.0.1406
    lsbdistdescription => CentOS Linux release 7.0.1406 (Core) 
    lsbdistrelease => 7.0.1406
    operatingsystemrelease => 7.0.1406

and current simple check `$::operatingsystemrelease < 6` fails on Puppet error `"Error: comparison of String with 6 failed at"`. Function **versioncmp** is better for version comparisons.