add service Invoice

Author: thiphamyp

Resources/config/services.xml

@@ -13,6 +13,7 @@
 
         <service id="zoho.api.addon" class="Zoho\Subscription\Api\Addon" parent="zoho.api.manager"></service>
         <service id="zoho.api.plan" class="Zoho\Subscription\Api\Plan" parent="zoho.api.manager"></service>
+        <service id="zoho.api.invoice" class="Zoho\Subscription\Api\Invoice" parent="zoho.api.manager"></service>
 
         <service id="zoho.array.cache" class="Doctrine\Common\Cache\ArrayCache"></service>