Redfish EventService schema implementation

Add Redfish EventService schema support for
EventService - GET and PATCH methods.
EventDestinationCollections - GET and POST methods.
EventDestination - GET, PATCH and DELETE methods.

URI's:
/redfish/v1/EventService
/redfish/v1/EventService/Subscriptions
/redfish/v1/EventService/Subscriptions/<id>

Tested:
 - Validated all default event config data using GET.
 - Validated supported/unsupported properties change.
 - Validated range parameters for retry and timeout.
 - Added new subscription using POST and validated using GET.
 - Modified subscription using PATCH and validated.
 - Validated delete subscription.
 - Validated negative case for eventTypes, RegistryPrefixes,
   mandate properties for POST etc.
 - Successfully ran the redfish validator tool.
   Counter({'metadataNamespaces': 1739, 'pass': 24,
            'skipOptional': 23, 'passGet': 3,
            'serviceNamespaces': 3})
   Validation has succeeded.

Signed-off-by: AppaRao Puli <apparao.puli@linux.intel.com>
Change-Id: I220de2cb85e73124753d95b7ee311f1c30e2cce4
diff --git a/redfish-core/lib/service_root.hpp b/redfish-core/lib/service_root.hpp
index 1f4343e..b6bd6e0 100644
--- a/redfish-core/lib/service_root.hpp
+++ b/redfish-core/lib/service_root.hpp
@@ -67,6 +67,8 @@
         res.jsonValue["CertificateService"] = {
             {"@odata.id", "/redfish/v1/CertificateService"}};
         res.jsonValue["Tasks"] = {{"@odata.id", "/redfish/v1/TaskService"}};
+        res.jsonValue["EventService"] = {
+            {"@odata.id", "/redfish/v1/EventService"}};
         res.end();
     }