Right now all roles assume that kibana has been deployed using the
stack and `kibana` group is defined in Ansible.
However if one need just to use journalbeat or filebeat roles to push
data to external Kibana - it's barely possible. Defining `kibana` group
is risky as open doors for installKibana playbook execution.
This patch adds variable kibana_target along with more role-specific
variables that allow to adjust thi behaviour and manually supply
Kibana endpoint to be configured.
Change-Id: Id2a42ae9c6146dcc9e86b15fee36372b95461d20
e013623e78