mistral requires auth_uri to point to v3 explicitly, to work

mistral fails with keystone v3, unless auth_uri explicitly references v3

in file:
kolla/ansible/roles/mistral/templates/mistral.conf.j2

currently v3 is not explicit
[keystone_authtoken]
auth_uri = {{ internal_protocol }}://{{ kolla_internal_fqdn }}:{{ keystone_public_port }}

what works for me:
[keystone_authtoken]
auth_uri = {{ internal_protocol }}://{{ kolla_internal_fqdn }}:{{ keystone_public_port }}/v3

also it looks like mistral project is not going to support this,

https://ask.openstack.org/en/question/53473/mistral-authorization-failed-the-resource-could-not-be-found-http-404/

Adding logs,

LOGS:

2016-08-24 15:12:29.606 1 WARNING mistral.actions.openstack.base [-] Traceback (most recent call last):
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/mistral/actions/openstack/base.py", line 79, in run
    method = self._get_client_method(self._get_client())
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/mistral/actions/openstack/actions.py", line 60, in _get_client
    keystone_endpoint = keystone_utils.get_keystone_endpoint_v2()
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/mistral/utils/openstack/keystone.py", line 114, in
    return get_endpoint_for_project('keystone')
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/mistral/utils/openstack/keystone.py", line 76, in get_endpoint_for_project
    response = client().tokens.get_token_data(token, include_catalog=True)
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/mistral/utils/openstack/keystone.py", line 35, in client
    auth_url=auth_url
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/keystoneclient/v3/client.py", line 231, in __init__
    self.authenticate()
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/positional/__init__.py", line 101, in inner
    return wrapped(*args, **kwargs)
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/keystoneclient/httpclient.py", line 578, in authenticate
    resp = self.get_raw_token_from_identity_service(**kwargs)
  File "/var/lib/kolla/venv/lib/python2.7/site-packages/keystoneclient/v3/client.py", line 317, in get_raw_token_from_identity_service
    _('Authorization failed: %s') % e)
AuthorizationFailure: Authorization failed: The resource could not be found. (HTTP 404)