Install lvm2 for cinder-volume LVM hosts

Currently the LVM2 package is installed by the
openstack_hosts role for the integrated build,
and by a test playbook for the role tests.

This does not seem sensible to me - it would
be better to ensure that the role installs the
distro packages it need in order to function
properly.

Additionally, it is not possible to setup a
loopback device inside an LXC container after
some recent updates to LXC. The secondary
cinder-volume service for LVM2 therefore
does not work, so it is removed from the
inventory to buy some time to come up with
an alternative solution.

Related-Bug: 1698831
Change-Id: Ie8a84a0412989c64fd896e8d781b8e9b2c153556

tests/inventory

@@ -3,13 +3,11 @@ localhost
 infra1
 keystone
 cinder
-cinder_vol
 
 [all_containers]
 infra1
 keystone
 cinder
-cinder_vol
 
 [rabbitmq_all]
 infra1
@@ -42,7 +40,6 @@ cinder
 
 [cinder_volume]
 localhost
-cinder_vol
 
 [cinder_all:children]
 cinder_api

vars/redhat-7.yml

@@ -36,5 +36,6 @@ cinder_volume_distro_packages:
 
 cinder_lvm_volume_distro_packages:
   - device-mapper-event
+  - lvm2
   - parted
   - scsi-target-utils

vars/ubuntu-16.04.yml

@@ -43,6 +43,7 @@ cinder_volume_distro_packages:
 
 cinder_lvm_volume_distro_packages:
   - dmeventd
+  - lvm2
   - parted
   - tgt
   - thin-provisioning-tools