Add a terminal / to quantum endpoint in keystone to correct the tempest network test request

To avoid the following error

    self._set_hostport(host, port)
  File "/usr/lib/python2.7/httplib.py", line 721, in _set_hostport
    raise InvalidURL("nonnumeric port: '%s'" % host[i+1:])
InvalidURL: nonnumeric port: '9696v2.0'
-------------------- >> begin captured logging << --------------------
tempest.config: INFO: Using tempest config file /root/tempest/etc/tempest.conf
--------------------- >> end captured logging << ---------------------