Add option to fail the flow build when a parallel job fails.

Build flow config on orcastrator job:

build("Build and publish artifacts")
parallel (
    {
        build("Slow tests 1")
    },
    {
        build("Slow tests 2")
    },
    {
        build("Fast tests 1")
    },
    {
        build("Fast tests 2")
    }
)

Lets say "Fast tests 1" fails on formatting check. Then the whole build should fail and make the executor will be available for other jobs. No need to finish "Slow tests 1", "Slow tests 2" and "Fast tests 2"

Might be related to JENKINS-18177 ("Allow to cancel both the flow and all running builds").

This feature is also mentioned in a comment, sep 13 2012:
https://wiki.jenkins-ci.org/display/JENKINS/Build+Flow+Plugin?focusedCommentId=63931160#comment-63931160