[WFCORE-105] Enabling Kerberos authentication over the HTTP management interface.

Please add...
```
// Validate this is being called against an actual resource.
// This makes valid the subsequent assumption that the relevant service will be installed.
context.readResource(PathAddress.EMPTY_ADDRESS, false);
```
Just today I diagnosed a support case issue where the console was calling an datasource subsystem op like this against all servers in a domain, even ones that didn't have the resource. The result was a very hard to diagnose problem because the missing service failure. So I have this subtlety on my mind. ;)