Feature: Slack integration (#783)

- Integrations architecture
- Slack integration

config/routes.rb

@@ -87,18 +87,26 @@ Rails.application.routes.draw do
           end
           resource :notification_settings, only: [:show, :update]
 
-          resources :webhooks, except: [:show]
+        resources :webhooks, except: [:show]
+        namespace :integrations do
+          resources :apps, only: [:index, :show]
+          resources :slack, only: [:create, :update, :destroy]
+        end
         end
       end
-
       # end of account scoped api routes
       # ----------------------------------
 
+      namespace :integrations do
+        resources :webhooks, only: [:create]
+      end
+
       resource :profile, only: [:show, :update]
       resource :notification_subscriptions, only: [:create]
 
       resources :agent_bots, only: [:index]
 
+      
       namespace :widget do
         resources :events, only: [:create]
         resources :messages, only: [:index, :create, :update]