Move to latest Redfish Service version

The latest version of the Redfish Service is 1.9.0.
Nothing preventing us from moving to it.
Find the Redfish Specification (DSP0266) here:
https://www.dmtf.org/dsp/DSP0266

Looks like code is already trying to use some of the 1.7.0
features:
"Added "Password Management" clause to describe functional behavior
for restricting access when an account requires a password change."
Eventing mechanism and ApplyTime.

Will want to use features like:
odata.context optional, query parameter clarification, and eventing
clarification.

Tested: Redfish Validator. Not really a valid test though.
        Ran Redfish-Service-Conformance-Check, didn't see
        additional errors.

Note: bmcweb still has a lot of Conformance Checker errors,
we are not in 100% complicance with Redfish specification.

Change-Id: I0acd28efa2aaa91149f53efddae530816fd41fff
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/redfish-core/lib/service_root.hpp b/redfish-core/lib/service_root.hpp
index 3b9adbf..0bf0ca1 100644
--- a/redfish-core/lib/service_root.hpp
+++ b/redfish-core/lib/service_root.hpp
@@ -48,7 +48,7 @@
             "/redfish/v1/$metadata#ServiceRoot.ServiceRoot";
         res.jsonValue["Id"] = "RootService";
         res.jsonValue["Name"] = "Root Service";
-        res.jsonValue["RedfishVersion"] = "1.6.1";
+        res.jsonValue["RedfishVersion"] = "1.9.0";
         res.jsonValue["Links"]["Sessions"] = {
             {"@odata.id", "/redfish/v1/SessionService/Sessions"}};
         res.jsonValue["AccountService"] = {