testing: use ceph vagrant box on ubuntu xenial mon osd mds rgw scenario

Signed-off-by: Alfredo Deza <adeza@redhat.com>

tests/functional/ubuntu/16.04/mon-osd-mds-rgw/vagrant_variables.yml

@@ -38,7 +38,13 @@ eth: 'eth1'
 disks: "[ '/dev/sdb', '/dev/sdc' ]"
 
 # VAGRANT BOX
-# Ubuntu: bento/ubuntu-16.04 or ubuntu/trusty64 or ubuntu/wily64
+# Ceph boxes are *strongly* suggested. They are under better control and will
+# not get updated frequently unless required for build systems. These are (for
+# now):
+#
+# * ceph/ubuntu-xenial
+#
+# Ubuntu: ceph/ubuntu-xenial bento/ubuntu-16.04 or ubuntu/trusty64 or ubuntu/wily64
 # CentOS: bento/centos-7.1 or puppetlabs/centos-7.0-64-puppet
 # libvirt CentOS: centos/7
 # parallels Ubuntu: parallels/ubuntu-14.04
@@ -46,7 +52,7 @@ disks: "[ '/dev/sdb', '/dev/sdc' ]"
 # For more boxes have a look at:
 #   - https://atlas.hashicorp.com/boxes/search?utf8=✓&sort=&provider=virtualbox&q=
 #   - https://download.gluster.org/pub/gluster/purpleidea/vagrant/
-vagrant_box: yk0/ubuntu-xenial
+vagrant_box: ceph/ubuntu-xenial
 #ssh_private_key_path: "~/.ssh/id_rsa"
 # The sync directory changes based on vagrant box
 # Set to /home/vagrant/sync for Centos/7, /home/{ user }/vagrant for openstack and defaults to /vagrant