##### SUMMARY
hall module:  the hall.com is not available
```
 19 description:
 20     - "The C(hall) module connects to the U(https://hall.com) messaging API and allows you to deliver notication messages to rooms."
...
 24   room_token:
 25     description:
 26       - "Room token provided to you by setting up the Ansible room integation on U(https://hall.com)"
...
 65 HALL_API_ENDPOINT = 'https://hall.com/api/1/services/generic/%s'
```
It looks like https://hall.com is not available
```
test:~$ ping hall.com
ping: hall.com: No address associated with hostname
test:~$ ping www.hall.com
ping: www.hall.com: Name or service not known
test:~$ host hall.com
hall.com mail is handled by 10 mxa.mailgun.org.
hall.com mail is handled by 20 mxb.mailgun.org.
test:~$ host www.hall.com
Host www.hall.com not found: 3(NXDOMAIN)
```
I can't find any information about this service exists nowadays or not

Therefore, the module must be removed or fixed.

##### ISSUE TYPE
- Documentation Report

##### COMPONENT NAME
```lib/ansible/modules/notification/hall.py```

##### ANSIBLE VERSION
```
2.8
```
headers = {'Content-Type': 'application/json'}
    payload = module.jsonify(payload)
    api_endpoint = HALL_API_ENDPOINT % (room_token)
    response, info = fetch_url(module, api_endpoint, data=payload, headers=headers)
    if info['status'] != 200:
        secure_url = HALL_API_ENDPOINT % ('[redacted]')
        module.fail_json(msg=" failed to send %s to %s: %s" % (payload, secure_url, info['msg']))
def main():
    module = AnsibleModule(
        argument_spec=dict(
            room_token=dict(type='str', required=True),
            msg=dict(type='str', required=True),
            title=dict(type='str', required=True),
            picture=dict(type='str',
                         default='http://cdn2.hubspot.net/hub/330046/file-769078210-png/Official_Logos/ansible_logo_black_square_small.png?t=1421076128627'),
        )
    )
    room_token = module.params['room_token']
    message = module.params['msg']
    title = module.params['title']
    picture = module.params['picture']
    payload = {'title': title, 'message': message, 'picture': picture}
    send_request_to_hall(module, room_token, payload)
    module.exit_json(msg="OK")
if __name__ == '__main__':
    main()