webhooks: Migrate most integrations to use check_send_webhook_message.

This commit migrates all of our webhooks to use
check_send_webhook_message, except the following:

beeminder: Rishi wanted to wait on this one.
teamcity: This one is slightly more work.

yo: This one is PM-only. I am still trying to decide whether we
    should have a force_private argument or something in
    check_send_webhook_message.

facebook: No point in migrating this, will be removed as part of
          #8433.

slack: Slightly more work too with the `channel_to_topics` feature.
       Warrants a longer discussion.

zerver/webhooks/gosquared/view.py

@@ -4,9 +4,9 @@ from django.http import HttpRequest, HttpResponse
 from django.utils.translation import ugettext as _
 
 from zerver.decorator import api_key_only_webhook_view
-from zerver.lib.actions import check_send_stream_message
 from zerver.lib.request import REQ, has_request_variables
 from zerver.lib.response import json_error, json_success
+from zerver.lib.webhooks.common import check_send_webhook_message
 from zerver.models import UserProfile
 
 BODY_TEMPLATE = '[{website_name}]({website_url}) has {user_num} visitors online.'
@@ -14,18 +14,13 @@ BODY_TEMPLATE = '[{website_name}]({website_url}) has {user_num} visitors online.
 @api_key_only_webhook_view('GoSquared')
 @has_request_variables
 def api_gosquared_webhook(request: HttpRequest, user_profile: UserProfile,
-                          payload: Dict[str, Dict[str, Any]]=REQ(argument_type='body'),
-                          stream: Text=REQ(default='gosquared'),
-                          topic: Text=REQ(default=None)) -> HttpResponse:
+                          payload: Dict[str, Dict[str, Any]]=REQ(argument_type='body')) -> HttpResponse:
     domain_name = payload['siteDetails']['domain']
     user_num = payload['concurrents']
     user_acc = payload['siteDetails']['acct']
     acc_url = 'https://www.gosquared.com/now/' + user_acc
     body = BODY_TEMPLATE.format(website_name=domain_name, website_url=acc_url, user_num=user_num)
-    # allows for customisable topics
-    if topic is None:
-        topic = 'GoSquared - {website_name}'.format(website_name=domain_name)
+    topic = 'GoSquared - {website_name}'.format(website_name=domain_name)
 
-    check_send_stream_message(user_profile, request.client, stream,
-                              topic, body)
+    check_send_webhook_message(request, user_profile, topic, body)
     return json_success()