Fix validate_cmd, previous addition of SystemCallError only works for Puppet 3.7, previous version throw different exception.  Wrapping in generic Exception catch all
Merge pull request #349 from cyberious/4.3.x

Fix validate_cmd, previous addition of SystemCallError only works for Puppet 3.7, previous version throw different exception.  Wrapping in generic Exception catch all
Merge branch '4.3.x'