Update to use operatingsystemmajrelease and do Integer comparison rather than String

When running a Debian Squeeze (6.0.7) client against a Debian Wheezy (7.1) master
received the following error:

comparison of String with 7 failed at /etc/puppet/modules/ssh/manifests/params.pp:24

Removing quotes to treat as Integer comparison rather than String and using only the
major release fact to compare against rather than potential multi-decimal version