errors while running runcmd lines should fail the first boot

This bug was originally filed in Launchpad as [LP: #1802316](https://bugs.launchpad.net/cloud-init/+bug/1802316)

Launchpad details

affected_projects = []

assignee = None

assignee_name = None

date_closed = None

date_created = 2018-11-08T14:44:21.837367+00:00

date_fix_committed = None

date_fix_released = None

id = 1802316

importance = wishlist

is_complete = False

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1802316

milestone = None

owner = mazerty

owner_name = Thomas JOUANNOT

private = False

status = triaged

submitter = mazerty

submitter_name = Thomas JOUANNOT

tags = []

duplicates = []

_Launchpad user **Thomas JOUANNOT(mazerty)** wrote on 2018-11-08T14:44:21.837367+00:00_

given a list of commands specified in a "runcmd" list, if a command fails i think it should prevent the next commands from running and mark the execution as failed
also, the power_state should be ignored.