This change updates the json_to_dhall task to provides a better
failure message.
This change also refactors the CR spec transformation
using jinja combinaison filter to be able to use the raw spec directly.
Finally this change removes a copy of the spec from the local playbook
by using the flat cr_spec file directly.
Change-Id: I6ed5c6746f01a8a277d50bdef317e56dfde5f66d