Parameterize the lockfile variable in the init script

The main reason for this is that "facter" isn't in the $PATH for root if you use
Puppet Enterprise, since PE is installed in /opt/puppet/ by default. Hence, the
init script will give an error if you run it with PE installed.
Merge pull request #39 from theasci/parameterize-lock-file

Parameterize the lockfile variable in the init script