This patch fixes multiple things:

* from validations_libs.validation_actions import show_validations_parameters

The generated file was containing the validations names and their
existing parameters as returned by the get_validations_parameters
method. But the file should only contains the parameters.

* from validations_libs.utils import get_validations_playbook

This method was supposed to get a list of validations playbooks
abs. path either by their names or their groups. This method was working
only when giving validation names but not with groups.

This patch fixes all the problems above and make the parameters
management work again.

Change-Id: Iec30cccade1234a127ef406ed13604cce45a72fd
Signed-off-by: Gael Chamoulaud (Strider) <gchamoul@redhat.com>