Add LVM Cinder support

It relies on loopback devices and is only meant for testing.
diff --git a/cinder/control/backend/lvm.yml b/cinder/control/backend/lvm.yml
new file mode 100644
index 0000000..976a80e
--- /dev/null
+++ b/cinder/control/backend/lvm.yml
@@ -0,0 +1,9 @@
+parameters:
+  cinder:
+    controller:
+      default_volume_type: lvm-driver
+      backend:
+        lvm-driver:
+          engine: lvm
+          type_name: lvm-driver
+          volume_group: cinder-volume