Adds support for installing Ansible roles from Galaxy based on a
requirements.yml file in the kayobe configuration repository.
Roles are installed during 'kayobe control host bootstrap' and upgraded
during 'kayobe control host upgrade'. Custom roles are defined in a
requirements file at '$KAYOBE_CONFIG_PATH/ansible/requirements.yml'. The
roles will be installed to '$KAYOBE_CONFIG_PATH/ansible/roles/'.
This forms the basis for supporting customisable extensions to the
standard workflows.
Change-Id: I4cd732623fc26986d5814be487c7930501ac7b7c
Story: 2001663
Task: 12599
9ec76f9e90