Add the new user and group for OpenvSwitch 2.8 version

OvS2.8, by default in fedora/centos/rhel, run as openvswitch:openvswitch
and when DPDK is enabled, it runs as openvswitch:hugetlbfs. Adding the
new user and group to the config.

Change-Id: I674cbd45e17906448dd54acfdf7a7059880b7278

kolla/common/config.py

@@ -974,6 +974,14 @@ USERS = {
     'almanach-user': {
         'uid': 42475,
         'gid': 42475,
+    },
+    'openvswitch-user': {
+        'uid': 42476,  # unused user
+        'gid': 42476,
+    },
+    'hugetlbfs-user': {
+        'uid': 42477,  # unused user, but we need the group for vhost socket
+        'gid': 42477,
     }
 }