Add method to register company callback url.

.gitignore

@@ -7,3 +7,4 @@
 /pkg/
 /spec/reports/
 /tmp/
+/.idea

lib/dingtalk/api/callback.rb

@@ -0,0 +1,23 @@
+module Dingtalk
+  module Api
+    class Callback < Base
+
+      def reg_callback url, tags = ['user_add_org', 'user_modify_org', 'user_leave_org', 'org_dept_create', 'org_dept_modify', 'org_dept_remove']
+        params = {
+            call_back_tag: tags,
+            token: Dingtalk.suite_token,
+            aes_key: Dingtalk.suite_aes_key,
+            url: url
+        }
+        http_post("register_call_back?access_token=#{access_token}", params)
+      end
+
+      private
+
+      def base_url
+        'call_back'
+      end
+
+    end
+  end
+end