There was previously an environment variable (``ANSIBLE_ROLE_FETCH_MODE``)
to set whether the roles in ansible-role-requirements.yml were fetched using
ansible-galaxy or using git, however the default has been git for some time
ansible since the use of the ``ceph-ansible`` respoitory for ceph deployment,
using ansible-galaxy to download the roles does not work properly. This
functionality has therefore been removed.
Change-Id: Icf804e40bb4903e45e4357de8c775606087bb5c4
72a87f6740