Run build in non-default node pool

[jalama]

Ideally we would build the Yocto project in a custom Node Pool where can allocate less of the larger c4.2xlarge servers. I think we would need to run runSh jobs to do this.

http://docs.shippable.com/platform/tutorial/workflow/using-runSh/#running-on-a-specific-node-pool

More about Node Pools: http://blog.shippable.com/windows-mac-centos-builds-announcements