Updated deprecated keystone_authtoken option
Updated deprecated keystone_authtoken option

* memcache_servers is a deprecated name for memcached_servers.
  See: keystonemiddleware/auth_token/__init__.py#n287

NOTE: memcache_serves in the cache section is valid option for
    oslo.cache.  See oslo_cache/_opts.py#n65

Depends-on: Id65f1bff8e38c777fa406d88ac6a2355d6033d94
Change-Id: I3e1230b139e710a0433e71ce118ca246d7c6a0e6

Mahito/devstack,nawawi/openstack,bigswitch/devstack,group-policy/devstack,nawawi/openstack,noironetworks/devstack,Mahito/devstack,richliu/devstack,group-policy/devstack,openstack-dev/devstack,openstack-dev/devstack,samgoon/devstack,noironetworks/devstack,bigswitch/devstack,bswartz/devstack,richliu/devstack,samgoon/devstack,dtroyer/devstack,dtroyer/devstack,bswartz/devstack