Failed pipeline plan should have a return code of 1

[nextrevision]

Whenever a pipeline-template plan fails due to an invalid template the return code is still 0 (see https://github.com/spinnaker/roer/blob/master/actions.go#L234). This makes testing templates in a CI system much harder.

Would be great if we could have a RC of 1

[benjaminws]

If I'm not mistaken, this was fix up by #29.