'create( trans, payload )
* POST /api/metrics:
record any metrics sent and return some status object
.. note:: Anonymous users can post metrics
:type   payload: dict
:param  payload: (optional) dictionary structure containing:
* metrics:          a list containing dictionaries of the form:
** namespace:       label indicating the source of the metric
** time:            isoformat datetime when the metric was recorded
** level:           an integer representing the metric\'s log level
** args:            a json string containing an array of extra data
:rtype:     dict
:returns:   status object'

@expose_api_anonymous
def create(self, trans, payload, **kwd):

    user_id = (trans.user.id if trans.user else None)
    session_id = (trans.galaxy_session.id if trans.galaxy_session else None)
    parsed_gen = self._parse_metrics(payload.get('metrics', None), user_id, session_id)
    self._send_metrics(trans, parsed_gen)
    response = self._get_server_pong(trans)
    return response
