[Review] Request from 'greygoo' @ 'SUSE/machinery/review_140731_dont_cut_error_messages'

Please review the following changes:
  * 32a5f11 Changed Cheetah exceptions to show all standard error output.
You're inside the `when Cheetah::ExecutionFailed` block, so this condition will always be true. I'd merge this block with the `else` block below, though, because both cases are about unexpected errors where we want to print instructions on how to report a bug, for example.

So the structure would then be
```ruby
case e
...
else
  ... # Print instructions on how to report a bug etc. here
  if e.is_a?(Cheetah::ExecutionFailed)
    ... # Collect stdout and stderr and print it
    exit 1
  else
    raise
  end
end
```