Determine if WebAPI has security enabled

[anthonysena]

As suggested here: #177 (comment).

Can we interrogate WebAPI to see if security is enabled? The answer is 'yes' if the version is 2.8 or higher. The WebAPI/info endpoint will provide those details as shown in the abbreviated JSON response:

{
	"version": "2.8.0",
	"buildInfo": {...},
	"configuration": {
		"security": {
			"samlActivated": false,
			"enabled": false,
			"samlEnabled": false
		},...
	}
}

So we might consider adding to the authenticate.R methods a check to this endpoint to see if authorization is even required.