Fix error handling when puppet is not installed

Bug introduced by 3b694955db500f23665d481b34a3e7d6878ea3d6. The error message
generated in response to an error in running 'puppet --version' itself
generated a new error by referencing a 'status' method that does not exist.
Merge pull request #196 from bitglue/fix_commanderror_handling

Fix error in error handling when puppet is not installed