switch to thias/puppet-sysctl instead of  duritong/sysctl 

duritong/sysctl doesn't compile, since the exec paths are not fully qualified

Also, duritong is writing directly the sysctl conf file, meaning that changes made by puppet can't be reverted or purged. Thias module is writing all modifications do sysctl.d and all changes can be reverted by doing purge on that dir.