Add GET method for Triggers

Added GET method for retrieving details of individual Trigger searched
by given Trigger name, details are extracted from Telemetry service

Tested:
- Added single Trigger and requested result from bmcweb via
  /redfish/v1/TelemetryService/Triggers/<triggername>
- Added multiple Triggers numeric and discrete with various parameters
  (empty, non-empty), and requested results from bmcweb via
  /redfish/v1/TelemetryService/Triggers/<triggername>
- Verified uris /redfish/v1/TelemetryService/Triggers/<triggername> by
  using Redfish-Service-Validator (all passed)

Signed-off-by: Lukasz Kazmierczak <lukasz.kazmierczak@intel.com>
Change-Id: I1c966b2f792324cc6f6a8784ad18a683e5ce7bd9
diff --git a/redfish-core/include/redfish.hpp b/redfish-core/include/redfish.hpp
index e56996d..2397df6 100644
--- a/redfish-core/include/redfish.hpp
+++ b/redfish-core/include/redfish.hpp
@@ -208,6 +208,7 @@
         requestRoutesMetricReportCollection(app);
         requestRoutesMetricReport(app);
         requestRoutesTriggerCollection(app);
+        requestRoutesTrigger(app);
     }
 };