backend-setup role fails on rhel7

[kristvanbesien]

When applying the gluster.infra role this fails during the last task of the backend-setup sub role. This against a RHGS3.5 on RHEL7 host.

The task that fails is this one:

- name: Regenerate new LVM filter rules
  shell: >
    vdsm-tool config-lvm-filter -y

This fails because vdsm-tool is an interactive command, that waits for some operator to answer with Yes or No to proceed. As a result the playbook there just hangs. On RHEL7 at least vdsm-tool does not have an -y option.