Make doGet implementations optional

There are cases in redfish where one may want to support ONLY a
POST/PATCH interface, and not support GET.  This patchset provides default
behavior for that case.

Change-Id: Ibd46c5dda2af543c491c1d6fba3d0adb65699db2
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/redfish-core/include/node.hpp b/redfish-core/include/node.hpp
index c2d331c..113514a 100644
--- a/redfish-core/include/node.hpp
+++ b/redfish-core/include/node.hpp
@@ -111,7 +111,10 @@
  protected:
   // Node is designed to be an abstract class, so doGet is pure virtual
   virtual void doGet(crow::response& res, const crow::request& req,
-                     const std::vector<std::string>& params) = 0;
+                     const std::vector<std::string>& params) {
+    res.result(boost::beast::http::status::method_not_allowed);
+    res.end();
+  };
 
   virtual void doPatch(crow::response& res, const crow::request& req,
                        const std::vector<std::string>& params) {