The skip list feature was available only via the API, this patch
allow the user to pass a file with the list of the validations
which he wants to skip during the run, example:
check-ram: hosts: all
reason: Wrong ram value
lp: https://lp.fake.net
check-cpu: hosts: undercloud
reason: Unstable validation
lp: https://lp.fake.net
Change-Id: I04059f9339085e0dcef1f018cad1be511ee7d3c7