limit the number of nodes that a job can be executed against. needed until we implement one shot execution ala https://github.com/rundeck/rundeck/issues/729
allow variables to be passed into template
better implementation from his @coderanger-ness
Merge pull request #9 from balanced-cookbooks/variables

allow variables to be passed into template
Merge pull request #8 from balanced-cookbooks/limit

limit the number of nodes that a job can be executed against.