'Abort a running task
**Example request**:
.. sourcecode:: http
POST /api/task/abort/c60be250-fe52-48df-befb-ac66174076e6 HTTP/1.1
Host: localhost:5555
**Example response**:
.. sourcecode:: http
HTTP/1.1 200 OK
Content-Length: 61
Content-Type: application/json; charset=UTF-8
"message": "Aborted \'1480b55c-b8b2-462c-985e-24af3e9158f9\'"
:reqheader Authorization: optional OAuth token to authenticate
:statuscode 200: no error
:statuscode 401: unauthorized request
:statuscode 503: result backend is not configured'

@web.authenticated
def post(self, taskid):

    logger.info("Aborting    task    '%s'", taskid)
    result = AbortableAsyncResult(taskid)
    if (not self.backend_configured(result)):
        raise HTTPError(503)
    result.abort()
    self.write(dict(message=("Aborted    '%s'" % taskid)))
