Add new node attribute 'classes:'

'classes:' allow to attach additional classes from 'system'
and 'service' models; or from 'cluster' model in the following
format:
          - cluster.${_param:cluster_name}....

Change-Id: I357c5ed3f06d666a4c5f9e7318d651c404eca139
diff --git a/inventory_examples/reduced_footprint_with_cfg01.yaml b/inventory_examples/reduced_footprint_with_cfg01.yaml
new file mode 100644
index 0000000..290e515
--- /dev/null
+++ b/inventory_examples/reduced_footprint_with_cfg01.yaml
@@ -0,0 +1,167 @@
+nodes:
+    cfg01.mcp11-ovs-dpdk.local:
+      reclass_storage_name: infra_config_node01
+      roles:
+      - infra_config
+      - linux_system_codename_xenial
+      classes:
+      - system.openssh.client.lab
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+
+    ctl01.mcp11-ovs-dpdk.local:
+      reclass_storage_name: openstack_control_node01
+      roles:
+      - infra_kvm
+      - openstack_control_leader
+      - openstack_database_leader
+      - openstack_message_queue
+      - features_designate_pool_manager_database
+      - features_designate_pool_manager
+      - features_designate_pool_manager_keystone
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+
+    ctl02.mcp11-ovs-dpdk.local:
+      reclass_storage_name: openstack_control_node02
+      roles:
+      - infra_kvm
+      - openstack_control
+      - openstack_database
+      - openstack_message_queue
+      - features_designate_pool_manager_database
+      - features_designate_pool_manager
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+
+    ctl03.mcp11-ovs-dpdk.local:
+      reclass_storage_name: openstack_control_node03
+      roles:
+      - infra_kvm
+      - openstack_control
+      - openstack_database
+      - openstack_message_queue
+      - features_designate_pool_manager_database
+      - features_designate_pool_manager
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+
+    prx01.mcp11-ovs-dpdk.local:
+      reclass_storage_name: openstack_proxy_node01
+      roles:
+      - openstack_proxy
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+
+    mon01.mcp11-ovs-dpdk.local:
+      reclass_storage_name: stacklight_server_node01
+      roles:
+      - stacklightv2_server_leader
+      - stacklight_telemetry_leader
+      - stacklight_log_leader_v2
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+
+    mon02.mcp11-ovs-dpdk.local:
+      reclass_storage_name: stacklight_server_node02
+      roles:
+      - stacklightv2_server
+      - stacklight_telemetry
+      - stacklight_log
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+
+    mon03.mcp11-ovs-dpdk.local:
+      reclass_storage_name: stacklight_server_node03
+      roles:
+      - stacklightv2_server
+      - stacklight_telemetry
+      - stacklight_log
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+
+    # Generator-based computes. For compatibility only
+    cmp<<count>>.mcp11-ovs-dpdk.local:
+      reclass_storage_name: openstack_compute_rack01
+      roles:
+      - openstack_compute
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+        ens5:
+          role: bond0_ab_ovs_vxlan_mesh
+        ens6:
+          role: bond1_ab_ovs_floating
+
+    gtw01.mcp11-ovs-dpdk.local:
+      reclass_storage_name: openstack_gateway_node01
+      roles:
+      - openstack_gateway
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+        ens5:
+          role: bond0_ab_ovs_vxlan_mesh
+        ens6:
+          role: bond1_ab_ovs_floating
+
+    dns01.mcp11-ovs-dpdk.local:
+      reclass_storage_name: openstack_dns_node01
+      roles:
+      - features_designate_pool_manager_dns
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+          single_address: ${_param:openstack_dns_node01_address}
+
+    dns02.mcp11-ovs-dpdk.local:
+      reclass_storage_name: openstack_dns_node02
+      roles:
+      - features_designate_pool_manager_dns
+      - linux_system_codename_xenial
+      interfaces:
+        ens3:
+          role: single_dhcp
+        ens4:
+          role: single_ctl
+          single_address: ${_param:openstack_dns_node02_address}