Change return code

Prior to this commit this resource was working but throughing an error
`err: /Stage[main]//Exec[node:parameters]/returns: change from notrun to
1 failed: rake node:parameters name=classroom.puppetlabs.vm
parameters=fact_is_puppetmaster=true returned 0 instead of one of [1] at
/root/foo.pp:9` because I forgot to set the exit code correctly