use webhook urls instead of encrypted configs

lib/ability.rb

@@ -22,5 +22,6 @@ class Ability
     can :manage, UserConfig, user_id: user.id
     can :manage, Account, id: user.account_id
     can :manage, AccessToken, user_id: user.id
+    can :manage, WebhookUrl, account_id: user.account_id
   end
 end